Extracted text: A = {a, b, c, d} X = {1, 2, 3, 4} Each choice defines a function whose domain is A and whose target is X. Select the function that has a well-defined inverse. а.f3 (а, 3), (b, 4), (с., 3), (d, 4)} O b.f%3{(a, 3). (b, 3). (с, 3), (d, 3)} О с.f3D (а, 3). (b, 4). (с, 2), (d, 1)} O d.f%3{(a, 3), (b, 4). (с, 2), (d, 4)}