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

Input: Consider Input: Plasma membranes encloses and defines the borders of cells.

Output: What encloses and defines the borders of cells?


Input: Consider Input: Destructive interference in waves occurs two troughs what things overlap.

Output: Destructive interference in waves occurs when what things overlap?


Input: Consider Input: At high altitudes there is lower atmospheric pressure than on the surface of the earth of the following best explains why the pressure inside a high-flying airplane must be controlled.


Output: Which of the following best explains why the pressure inside a high-flying airplane must be controlled?