Given a scientific passage and an answer, generate a question for the given answer.

Example Input: Passage: Pea plants are naturally self-pollinating. In self-pollination , pollen grains from anthers on one plant are transferred to stigmas of flowers on the same plant. Mendel was interested in the offspring of two different parent plants, so he had to prevent self-pollination. He removed the anthers from the flowers of some of the plants in his experiments. Then he pollinated them by hand with pollen from other parent plants of his choice. When pollen from one plant fertilizes another plant of the same species, it is called cross-pollination . The offspring that result from such a cross are called hybrids. Answer: cross-pollination
Example Output: What is it called when pollen from one plant fertilizes another plant of the same species?

Example Input: Passage: Climate is the most important factor in determining the type of soil that forms in a particular area. Answer: climate
Example Output: What is the most important factor in determining the type of soil that forms in a particular area?

Example Input: Passage: Oxygenated blood is transported by the circulatory system from lungs to tissues throughout the body. Answer: circulatory
Example Output:
Oxygenated blood is transported by what system?