For each of the following collections of sets, determine, if possible, a system of distinct representatives. If

Question:

For each of the following collections of sets, determine, if possible, a system of distinct representatives. If no such system exists, explain why.
(a) A1 = {2, 3, 4}, A2 = {3, 4}, A3 = {1}, A4 = {2, 3}
(b) A1, = A2 = A3 = {2, 4, 5}, A4 = A5 = {1, 2, 3, 4, 5}
c) A1 = {1, 2}, A2 = {2, 3, 4}, A3 = {2, 3}, A4 = {1, 3}, A5 = {2, 4}