State if each of the following is a (write the letter only): A. Not a function, just a relation B. A 1-1 function or injection, but not an onto function C. An onto function or surjection, but not 1-1 function D. A one-to-one correspondence or bijection 1. f: Z'(negative integers) → Z"(positive integers) where f(x) = |2x| 2. f: Q N where f(x) = 1 + 1/x 3. f: R R where f(x) = 2x + 4