Answer
The equation matches with the graph labeled as IV.
Work Step by Step
$x^2+\frac{y^2}{9}=1$
$\frac{x^2}{1}+\frac{y^2}{9}=1$
$\frac{x^2}{1^2}+\frac{y^2}{3^2}=1$
$3\gt1$: major axis is vertical.
Equation when major axis is vertical:
$\frac{x^2}{b^2}+\frac{y^2}{a^2}=1$
So,
$a^2=3^2$
$a=3$
Vertices: $(0,±a)=(0,±3)$
The equation matches with the graph labeled as IV.