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

1. between 2 and 10
2. between 10 and 20
3. between 20 and 30
4. between 30 and 40
5. greater than 40

key: E

Please help. NN! Thanks a lot!

好像是N!+1的最小质因子大于N

h(100)=2*（50！）

所以...

记不太清了