AMC 8 1988 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? $\text{(A)}\ 2 \text{(B)}\ 3 \text{(C)}\ 4 \text{(D)}\ 5 \text{(E)}\ 6$