Consider the following functions from {a, b, c, d] to itself. Classify them as injective, surjective, bijective, or neither A. f (a) = b, f (b) = a, f (c) = c, f (d) = d B. f (a) = b, f (b) = b, f (c) = d, f (d) = = C C. f (a) = a, ƒ (b) = b, f (c) = c, f (d) = d A. f (a) = b, f(b) = a, f (c) = c, f (d) = d