Problem
1988 AJHSME Problem 16
Placing no more than one \text{X} in each small square, what is the greatest number of \text{X}'s that can be put on the grid shown without getting three \text{X}'s in a row vertically, horizontally, or diagonally?
\text{(A)}\ 2 \qquad \text{(B)}\ 3 \qquad \text{(C)}\ 4 \qquad \text{(D)}\ 5 \qquad \text{(E)}\ 6
![[asy] for(int a=0; a<4; ++a) { draw((a,0)--(a,3)); } for(int b=0; b<4; ++b) { draw((0,b)--(3,b)); } [/asy]](/static/aops/1161c2f219124fd219c171f81bebebb89efeb9a7.png)
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