2. Let f: A → B and g: B C be functions. Prove or disprove each of the following: (a) If both f and g are one-to-one then go f is one-to-one. (b) If go f is one-to-one then f is one-to-one. (c) If go f is one-to-one then g is one-to-one. (d) If go f is one-to-one and f is onto then g is one-to-one.