UKMT Pink Kangaroo, 2021

Combinatorics Difficulty 2.0 Junior Find the answer United Kingdom

In the $4 \times 4$ grid some cells must be painted black. The numbers to the right of the grid and those below the grid show how many cells in that row or column must be black. In how many ways can this grid be painted?

(A) $1$ (B) $2$ (C) $3$ (D) $5$ (E) more than $5$

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