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

Input: Consider Input: Aqueous solution is used to describe a solution in which water is the solvent.

Output: What term is used to describe a solution in which water is the solvent?

Input: Consider Input: The nuclear envelope is a double-layered plasma membrane like the cell membrane, although without membrane proteins.

Output: The nuclear envelope is a double-layered plasma membrane like the cell membrane, although without what?

Input: Consider Input: Exposure to ultraviolet radiation can increase the amount of pigment in the skin and make it appear darker.
Output: Exposure to what can increase the amount of pigment in the skin and make it appear darker?