Given the following sets, find the set a' n (buc) u = {1, 2, 3, 8} a = {1, 2, 3, 5) b = {2,3,4} c = {1, 2, 3, 4, 5) select the correct choice below and, if necessary, fill in the answer box to complete your choice. o a. a' (buc) = {} (use a comma to separate answers as needed. use ascending order.) ob. a' (buc) is the empty set.