Using the joint probability table below, determine the marginal distribution of X. -1 0 3 0.15 0 0.05 5 0.05 0.15 0.05 7 0.15 0.3 0.1 a) O X -1 0 P(X) 0.15 0.3 0.1 b) O X -1 0 P(X) 0.35 0.45 0.2 c) O X P(X) 0.2 0.25 0.55 d) o X P(X) 0.15 0 0.05