2. Determine whether each of these functions from {a,b,c,d) to itself is one-to-one/onto. (a) f(a) = 6, 6) = a, f(C) = c f(d) = 0 (b) f(a) = 6,f() = b, f(c) = d, f(d) = 0 (c) f(a) = d, f(0) = b, f (c) = c f(d) = d