## Precalculus (10th Edition)

Because the center of the ellipse is in the origin and the major axis is the x-axis, the equation of the ellipse here has the form $\frac{x^2}{a^2}+\frac{y^2}{b^2}=1$. Here $a=4\\a^2=16$, $b=2\\b^2=4.$ Hence the equation is: $\frac{x^2}{16}+\frac{y^2}{4}=1$, thus the answer is c).