Q. 44 What is the minimum number of ordered pairs of non-negative numbers that should be chosen to ensure that there are two pairs (a, b) and (c, d) in the chosen set such that “a ≡ c mod 3” and “b ≡ d mod 5”
(A) 4
(B) 6
(C) 16
(D) 24
Answer: (C)
Explanation: