TASK DEFINITION: Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
PROBLEM: Simple carbohydrates can be classified in terms of chain length.

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

PROBLEM: A diet rich in calcium and vitamin d may reduce the risk of osteoporosis and related bone fractures.

SOLUTION: A diet rich in calcium and what vitamin may reduce the risk of osteoporosis and related bone fractures?

PROBLEM: The rocks athe mid-ocean ridge are nearly free of sediment.

SOLUTION:
The rocks athe mid-ocean ridge are nearly free of what?