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

Ex Input:
Passage: Destructive interference in waves occurs when two troughs overlap. Answer: two troughs

Ex Output:
Destructive interference in waves occurs when what things overlap?

Ex Input:
Passage: Fats may be either saturated or unsaturated. A saturated fat is a fat that consists of triglycerides whose carbon chains consist entirely of carbon-carbon single bonds. Therefore, the carbon chains are saturated with the maximum number of hydrogen atoms possible. An unsaturated fat is a fat that consists of triglycerides whose carbon chains contain one or more carbon-carbon double bonds . A fat with one double bond is called monounsaturated, while a fat with multiple double bonds is called polyunsaturated (see Figure below ). Answer: saturated and unsaturated

Ex Output:
What are the two types of fats?

Ex Input:
Passage: Earthworms are important deposit feeders that help form and enrich soil. Answer: soil

Ex Output:
Earthworms are important deposit feeders that help form and enrich what material?