TASK DEFINITION: Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
PROBLEM: Certain air pollutants form acid liquid when dissolved in water droplets in the air.

SOLUTION: Certain air pollutants form which liquid when dissolved in water droplets in the air?

PROBLEM: Optics explains the behavior of visible light and electromagnetic waves.

SOLUTION: What type of physics explains the behavior of visible light and electromagnetic waves?

PROBLEM: The “knee-jerk" motion that people involuntarily perform after being struck in the knee in a certain way is an example of a reflex

SOLUTION:
The “knee-jerk" motion that people involuntarily perform after being struck in the knee in a certain way is an example of what kind of behavior?