Answer: 4 pairs. Explanation: Let N = total number of pairs. The phrase “all pairs are black except 3” means there are 3 pairs that are not black → number of black pairs = N – 3. Similarly: white pairs = N – 3; brown pairs = N – 3; grey pairs = N – 3. Since pairs must fit all conditions, Nicholas must have 1 black, 1 white, 1 brown, 1 grey. Why? Because with 4 pairs, each color leaves exactly 3 pairs of other colors → satisfying each statement. Therefore, N = 4 pairs.