Select the correctly punctuated sentence.

it's time for the class to end but mr. johnson doesn't realize that.
it's time for the class to end, but mr. johnson doesn't realize that.
it's time for the class to end; but mr. johnson doesn't realize that.

many were disgusted, nauseated and shook their heads with disapproval upon finding out about the recycling of water process. however, they do not seem to understand that this process actually saves water.

although individuals may argue that it is unhealthy, and or unsafe to drink water that is "from toilet to tap" , the water is 100% safe to drink and involves forcing the water across a membrane, which "removes   any impurities, including viruses, pharmaceuticals and dissolved minerals" , according to paul rozin, a psychology professor who studies revulsion.

i agree that that the thought of drinking water that once ran through someones kitchen sink isn't quite appealing, but recycled wastewater is safe to drink. it also saves water. "the city produces nine million gallons a day" claims russell schreiber, the city’s director of public works.

recycled waste water has absolutely no health concerns whatsoever. when wastewater goes into a system, it's absorbed back into the ground. thus, it goes into a sewer system, then goes through a treatment process that removes contaminants before being released. nonetheless, there is no problem in drinking water that has been recycled.

"in drought-ed california, there are six state agencies that use wastewater that comes from an intellectual property source," according to the university of california, riverside. studies show that this water is completely safe to drink, however, it still doesn't mean people are going to happily pour it in a water glass.

researchers hope it "may make consumers more amenable to drinking recycled wastewater," extraordinarily, women who have a higher "disgust reaction" and make most consumer purchasing decisions.

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