Let A = {1,2,3,4} and B = {a, b, c, d}. Define F = {(1, a), (2, b), (3, c), (4, d)} G = {(1, a), (2, c), (3, b), (3, c), (4, d)} H = {(1,a), (2, b), (3, b), (4, d)} (a) Is Fa function or only a relation? Explain why. (b) Is G a function or only a relation? Explain why. (c) Is H a function or only a relation? Explain why. (d) Determine |A x B. (e) Is Fa bijection? If yes, prove it. If not, explain why not. (f) Is G a bijection? If yes, prove it. If not, explain why not. (g) Is H a bijection? If yes, prove it. If not, explain why not.