我矫情了呀！

emmayahan

(n-x) + (n-y) + (n-c) + (n-k)
What is the value of the expression above
(1)The average (arithmetic mean) of x, y, c, and k is n.
(2)x, y, c, and k are consecutive integers.

请问各位大仙这道题之所以选A是因为把n默认为常量嘛？
谢谢！