Question

what is the cross - section of a right cylinder that is perpendicular to the base?
circle
rectangle
square
triangle

Explanation:

Step1: Recall cylinder properties

A right - cylinder has circular bases and straight, parallel sides.

Step2: Visualize perpendicular cross - section

When a cross - section is perpendicular to the base of a right - cylinder, it cuts through the cylinder parallel to its height.
Since the sides of a right - cylinder are straight and parallel to the height, the cross - section is a rectangle. A square is a special case of a rectangle, but we are looking for the general shape. A circle is the cross - section parallel to the base, and a triangle cannot be formed as a cross - section perpendicular to the base of a right - cylinder.

Answer:

B. Rectangle