The function f is defined for all positive integers n by the following rules: f(n) is the number of postive integers each of which is less than n and has no positive factor in common with n other than 1. If p is a prime number then f(p)=
A) p-1
B) p+1
C) (p+1)/2
D) (p-1)/2
E) 2
Explanation would be appreciated.
A) p-1
B) p+1
C) (p+1)/2
D) (p-1)/2
E) 2
Explanation would be appreciated.
