Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

Input: Consider Input: Collision frequency is greater for homogeneous category of catalysts, which also tend to be more sensitive to temperature and more 'expensive'.

Output: Collision frequency is greater for what category of catalysts, which also tend to be more sensitive to temperature and more 'expensive'?


Input: Consider Input: Certain air pollutants form acid liquid when dissolved in water droplets in the air.

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


Input: Consider Input: The plasma membrane controls what goes in and out of a cell.


Output: What controls what goes in and out of a cell?