GMAT中GWD的数学题For which real numbers x is the expression1/[(x-

GMAT中GWD的数学题For which real numbers x is the expression1/[(x-2)(x+1)] not defined?
看不懂题目意思,
A.x = 0 only
B.x = 2 only
C.x = –1 only
D.x = –1 or 2
E.x = –1,0,or 2

For which real numbers x is the expression1/[(x-2)(x+1)] not defined?
意思是：以下四个选项中x对于函数1/[(x-2)(x+1)]没有意义的是?
答案选C.