Answer:
Second Option is correct that is the sum of the focal radii.
Explanation:
Given: Ellipse
To find: Length of the Major Axis.
Focal Radii is the length of the line connecting the focus of ellipse and a point on the ellipse.
We know that Sum of Focal Radii is a constant and Equal to the Length of the Major Axis.
Therefore, Second Option is correct that is the sum of the focal radii.