Choices: 1. Exfoliation; 2. amble; 3. bite animals; 4. produce light; 5. grass; 6. reproduce; 7. sweating; 8. respirate;
Given those answer options, answer the question: You are presented with the quiz "What do plants do during the day?"   But you don't know the answer, so you turn to your teacher to ask for hints. He says that "plants release oxygen during the day but not during the night" and "oxygen exchange is needed for plant respiration".   So, what's the best answer to the question?
A:
8.