Question

The figure below is a square pyramid. Which of the following could not be a cross section in the figure?

Square
Rectangle that is not a square
Trapezoid
Isosceles triangle

Answer 1

if you run a plane like in the picture below, I don't think you could get an isosceles triangle, namely, a triangle with two equal sides.

Answer 2

Answer:

A rectangle that is not a square is the actual answer.