Sorry, I did not notice: "...then n can't be"
For your problem
So, right answers are:
A) 7
B) 12
C) 9
If there exists a non zero term independent of x in the expansion of [ x^2 - ((2)/(x)^3)]^n , then n can't be:
A) 7
B) 12
C) 9
D) 15
More than one options may be correct.