Consider the push-down automaton M = (K, sigma, Gamma, Delta, s, F) where K = {s, f}, sigma = {a, b}, Gamma = {a, 6}, F = {f}, and Delta consists of the following transitions: ((s, a, e), (s, b)), ((s, b, e), (s, a)), ((s, e, e), (f, e)), ((f, a, a), (f, e)), ((f, b, b), (f, e)). Which of the following strings are in L(M)? Write the letters of all strings that are in L(M) here: ____ a) ba b) bbbaaabbb c) aabaabb d) aabb e) abaaba f) abab