Find the equation of an ellipse that satisfies the following conditions: $a = 4$ and Foci = $(\pm3,0)$

Question

$\begin{array}{1 1}\frac{x^2}{16}+\frac{y^2}{7}=1 \\ \frac{x^2}{16}+\frac{y^2}{7}=1 \\ \frac{x^2}{7}+\frac{y^2}{16}=1 \\ \frac{x^2}{7}-\frac{y^2}{16}=1\end{array}$