TASK DEFINITION: Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
PROBLEM: Control rods play an important role in the modulation of the nuclear chain reaction.

SOLUTION: What play an important role in the modulation of the nuclear chain reaction?

PROBLEM: Cancer occurs most often in adults over fifty age.

SOLUTION: Cancer occurs most often in adults over what age?

PROBLEM: Bogs develops in depressions where water flow is low or nonexistent.

SOLUTION:
What develops in depressions where water flow is low or nonexistent?