求助一道PREP上的题

how many different prime numbers are factors of the positive integer n

(1)four different prime numbers are factors of 2n

(2)four different prime numbers are factors of n ^2

感激不尽。。。

B

1）2n may add 2 as a prime factor to n (suppose n has no factor as 2).

2)n^2=n*n will add no PRIME factor to n. So the number of prime factors of n^2 equals that of n.