Let r = {(a, b), (a, c), (c, d), (a, a), (b, a)}. What is r ◦ r, the composition of r with itself? What is r⁻¹, the inverse of r? Is r, r ◦ r, or r⁻¹ a function?

A) {(a, b), (a, c), (c, d), (b, a)}; {(b, a), (c, d), (a, c), (a, b)}; Yes
B) {(a, b), (a, c), (c, d)}; {(c, d), (a, c), (a, b)}; No
C) {(b, a), (c, d), (a, c), (a, b)}; {(a, b), (a, c), (c, d)}; Yes
D) {(c, d), (a, c), (a, b)}; {(a, b), (a, c), (c, d)}; No