Circle the letter of each sentence that is true about life in the ocean. a. in the euphotic zone, phytoplankton use sunlight to produce food. b. phytoplankton is the basis of most oceanic food webs. c. photosynthesis occurs from the surface to deep into the abyssal zone of the ocean. do. the neritic zone covers about 5 percent of the world's ocean, but supports 90 percent of the world's commercial fisheries.