What is the primary function of ethene in plant biology?

The correct option is To control cell division and fruit ripening.. This answer is correct because it matches the approved learning objective to explain (HT only) that ethene controls cell division and fruit ripening in the subtopic Control and coordination.

The correct option is To control cell division and fruit ripening.. To control cell division and fruit ripening. is correct because it directly supports the approved learning objective to explain (HT only) that ethene controls cell division and fruit ripening. This belongs to the subtopic Control and coordination within Plant hormones (biology only), so the explanation must stay tied to that curriculum context. The other options are incorrect because they either do not answer this learning objective, use a vague statement, or move away from Control and coordination.