The word "VICISSITUDE" refers to a change or variation occurring in the course of something. It often implies shifts in circumstances, often in a challenging or unwelcome way.
Based on the above reasoning, the correct answer is Mutability, as it best captures the meaning of changeability intrinsic to "vicissitude."
If the price of a commodity increases by 25%, by what percentage should the consumption be reduced to keep the expenditure the same?