Divisibility of large number This was a question asked in a competitive exam:

$(300^{3000} -1 )$ is divisible by
a) $401$ b) $501$ c) $301$ d) $901$

The answer is $301$. Not sure how they arrived at the answer. Can somebody explain ?

Let us consider the polynomial $x^n-1$ where $n$ is even, then $-1$ is a root of the polynomial and so it is divisible by $x-(-1)=x+1$. Put $x=300,n=3000$ to get the answer.
