Correct option is A
The correct answer is (a) They give out oxygen.
· Green plants in the sea (such as phytoplankton and algae) perform photosynthesis, a process in which they take in carbon dioxide and release oxygen.
· This oxygen is dissolved in the water and helps fish and other aquatic organisms to respire.
Information Booster:
· Photosynthesis is crucial for maintaining the oxygen levels in aquatic ecosystems, which in turn supports the respiration of marine life.