Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

Input: Consider Input: Oxygen gas is given off by plants.

Output: Which gas is given off by plants?

Input: Consider Input: Terrestrial biomes are classified by climatic factors and types of primary producers.

Output: What are classified by climatic factors and types of primary producers?

Input: Consider Input: Ovulation takes place in the ovary and is part of the menstrual cycle.
Output: Ovulation takes place in what organ and is part of the menstrual cycle?