Let o(1) 1, and for any integer n >1, 1et o(r) denote the number of positive integers less than n and relatively prime to n. the value of o(16) is (a) 7 (b) 8 (

Let o(1) 1, and for any integer n >1, 1et o(r) denote the number of positive integers less than n and relatively prime to n. The value of o(16) is (a) 7 (b) 8 (c) 6 () d) 5