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

Ex Input:
Passage: An ecosystem includes the living organisms (all the populations) in an area and the non-living aspects of the environment ( Figure below ). An ecosystem is made of the biotic and abiotic factors in an area. Answer: ecosystem

Ex Output:
What includes the living organisms in an area and the non-living aspects of the environment?

Ex Input:
Passage: Simple carbohydrates can be classified in terms of chain length. Answer: simple

Ex Output:
Which carbohydrates can be classified in terms of chain length?

Ex Input:
Passage: Water, carbon dioxide, and oxygen are important agents of chemical weathering. Answer: oxygen

Ex Output:
Water, carbon dioxide, and what other element are important agents of chemical weathering?