Answer:
Option (b) is correct.
The cross-section of the cone and the plane is an ellipse.
Explanation:
Given : A cone is cut by a plane as shown, where the plane is not parallel to the base.
We have to determine the shape of the cross-section of the cone and the plane.
Since, The cone is cut by the plane which is not parallel to its base.
a > b
There a is the horizontal distance between the slant height of cone.
and b is vertical distance.
Thus, when a > b

Thus, The cross-section of the cone and the plane is an ellipse.