The function F is defined for all positive integers n by the following rule: f(n) is the number of position integer each of which is less than n, and has no position factor in common with n other than 2. If p is any prime number then f(p)=	Choose the correct choice:
A) p-1  B) p-2  C) (p+1)/2  D) (p-1)/2  E) 2
The confusing moment in this question is its wording. Basically question is: how many positive integers are less than given prime number p which has no common factor with p except 1.   Well as p is a prime, all positive numbers less than p have no common factors with p (except common factor 1). So there would be p-1 such numbers (as we are looking number of integers less than p).   If we consider p=7 how many numbers are less than 7 having no common factors with 7: 1, 2, 3, 4, 5, 6 --&gt; 7-1=6.   Answer: 2.
<result>E</result>
The function F is defined for all positive integers n by the following rule: f(n) is the number of position integer each of which is less than n, and has no position factor in common with n other than 2. If p is any prime number then f(p)=