AHSME 1969 Problem 19

The number of distinct ordered pairs $(x,y)$ where $x$ and $y$ have positive integral values satisfying the equation $x^4y^4-10x^2y^2+9=0$ is: $\text{(A) } 0 \text{(B) } 3 \text{(C) } 4 \text{(D) } 12 \text{(E) } \infty$