Which sentence correctly uses a comma to separate the introductory phrase? before researchers are granted access to the rare-book stacks, they must be approved through a security screening process. before, researchers are granted access to the rare-book stacks they must be approved through a security screening process. before researchers are granted access, to the rare-book stacks they must be approved through a security screening process. before researchers are granted access to the rare-book stacks they must be approved through, a security screening process.

the answer is a

explanation:

concepts for wave energy have existed since the 1800s, anyway current wave technology started during the 1940s with the tests of researcher yoshio masuda. financing into wave energy technology has as of late expanded because of the requirement for renewable energy sources. the principal wave power plant on the planet opened in 2008 at the agucadoura wave homestead in portugal. tidal power to turn water haggles grains was utilized as far back as roman occasions and the medieval times. using tidal power for power is genuinely later, however the expenses have been too high to even consider making it a noteworthy energy source. ongoing mechanical advances have demonstrated that it could turn into a focused and feasible source. it is obscure precisely how exorbitant the venture would be; in any case, it is evaluated at around $16 billion. it is anticipated that the undertaking will take 9 years to assemble. hydroelectric energy would be accommodated the uk, and this is perfect and maintainable. there would likewise be wind generators on the blast, which would give progressively renewable energy to the uk. this would imply that less fossil fuels will be utilized, thusly lessening co2 discharges and diminishing the effect of global warming. it would assist the uk with meeting the kyoto convention co2 emanation focus by diminishing the (by 2020). be that as it may, there are an assortment of animal groups in the severn estuary where the blast will be fabricated, and their natural surroundings will be pulverized if the prepares. "the entire of the severn estuary is home to nearly 65,000 different types of water and swimming feathered creatures. it is a site of logical intrigue" said martin splash. the severn estuary is significant for the transient fish that go through the estuary on their approach to crisp water generating locales. the between tidal area gives nourishment to more than 85,00 water winged creatures, and speaks to 7% of the all out uk's estuaries-and this area would be upset by the structure of the torrent. the torrent would probably cause seaside disintegration in areas, for example, level holm-and this would diminish living spaces. additionally, individuals state that the torrent would be a blemish, and ruin the nearby scene because of the enormous measure of cement and the breeze turbines on the top.the area is useful for structure the power plant in light of the fact that during spring tides, the tide plentifulness can achieve 11 meters (36 feet). likewise, the gulf is a limited 15 kilometers (9 miles) crosswise over at the area proposed, and the site could lessen coal discharges in the area by 3 percent by supplanting fossil fuel power. tidal power plants should be worked in areas that reason directing of tidal water. the thin opening to a cove, for instance, will constrain the tidal waters to rise and fall quickly. this will make the waters stream through at an extraordinary speed. a fitting area should likewise have an enormous change among elevated and low tides. at the very least, there ought to be a distinction of 5 meters. a tidal power plant worked in such an area will be exceptionally productive at creating power. utilizing tide for power is productive in light of the fact that a great deal of electrical power is created. tidal power plants are equipped for changing over the development of water into usable power. tides give a standout amongst the most steady wellsprings of energy. review that tides are brought about by the gravitational powers of the sun and the moon. in contrast to fossil or atomic fuels, tidal power utilizes a boundless wellspring of energy as its info. it tends to be over the top expensive to fabricate the tidal power plant structure at first. in any case, when the underlying structure is fabricated the fuel is consistent and unsurprising. presently, here are some intriguing realities about tidal power plants. tidal turbines are more costly to construct and keep up than wind turbines, yet produce more energy. they additionally produce energy all the more reliably as the tide is ceaseless while the breeze doesn't generally blow. wave and tidal energy converters are situated close to the coastline. it is simpler to introduce, keep up, catch the energy, and recover the energy when they are found near the coast. the us has no tidal power plants. at long last, there are two existing enormous tidal floods on the planet today. one is in france and the other in canada.

sincerely,

buckster buckswood