By definition, the Standard form of the equation of an ellipse is:
Where the center is:
When its center is at the Origin, the equation is:
When:
Where:
It is horizontal.
And when:
Where:
It is vertical.
In this case, you know that this ellipse is centered at the Origin, its vertex is:
And the co-vertex is at:
Analyzing the information given in the exercise, you can idenfity that:
Therefore, you can substitute values into the equation
You get:
The answer is: Last option.