Answer:
Option B. Major axis.
Explanation:
An ellipse uses two axis, major and minor. Major axis is the larger one and minor axis is smaller.
Now we come to the question.
Here extreme points of the red line are on the ellipse are more distant than the extreme points of the axis perpendicular to the red line.
Therefore red line shows the Major axis of the ellipse drawn.
Option B. is the correct option.