If the polynomial x^5 − 10^5 can be split as the product of the polynomials x − 10 and a, what is a?

a) x^4 - 99,990
b) x^4+10x^3+100x^2+1000x -10,000
c) x^4+10x^3+100x^2+1,000x+10,000
d)x^4+10x^3+100x^2+1000x + 10000/x-10
e)x^4 - 99990/x-10

please help !,