What is the output when following code is executed ? names1 = ['Amir', 'Bear', 'Charlton', 'Daman'] names2 = names1 names3 = names1[:] names2[0] = 'Alice' names3[1] = 'Bob' sum = 0 for ls in (names1, names2, names3): if ls[0] == 'Alice': sum += 1 if ls[1] == 'Bob': sum += 10 print sum a) 11 b) 12 c) 21 d) 22