I can't figure out how to do this problem!

For every positive even integer n, the function h(n) is defined to be the product of all the even integers 2 to n, inclusive. If p is the smallest prime factor of h(100)+1, then p is

a) between 2 and 10
b) between 10 and 20
c) between 20 and 30
d) between 30 and 40
e) greater than 40