UPSC NDA Math Model Paper 5

Here, A = {1, 2}, B = {2, 3) and C = {3, 4)
A × B = {(1, 2), (1, 3), (2, 2), (2, 3)}
A × C = {(1, 3), (1, 4), (2, 3), (2, 4)}
(A × B) ∩ (A × C) = {(1, 3), (2, 3)}
∴ Number of elements = Cardinality = 2
Hence, option (3) is correct.