The side-view of a cone appears as:

Correct option is A

The side-view of a cone appears as a triangle. This is because when you view a cone from the side, you are only seeing the slant side of the cone, which forms a triangle. The base of the cone is not visible from the side, so the side view is simply a triangle. The triangle's height is the slant height of the cone, and its base is the diameter of the cone's base.