Which of the following is perfect number?
A.
There are infinitely many prime p,such that p+2 is also prime.
B.
n is the sum of its divisors,excluding n itself.
C.
When integer n>2,there are no positive integer solutions x,y,z of equation x n +y n =z n .
D.
For any even number n>2, n is the sum of two primes.