HW Score: 40%, 6 of 15 Question 7, 7.2.29 > O Points: 0 of 1 Let U = {6, 7, 8, 9, 10, 11, 12} and A = {7, 9, 11, 12}. Find A'. . . . . . Select the correct choice below and, if necessary, fill in the answer box to complete yo answer. O A. A' = (Use a comma to separate answers as needed.) O B. A' is the empty set