Select from the following.
(I) When the sun is out;
(II) heat produced;
(III) in the autumn season;
(IV) flow of electrons;
(V) When there is a full moon;
(VI) During nighttime hours;
(VII) When the stars are out;
(VIII) metabolic reaction;

You are presented with the quiz "When do plants release oxygen?" 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 "when it is day the sun is out". So, what's the best answer to the question?
Answer:
(I)