A. cone
D. triangular pyramid
E. square pyramid
(Look at the photo at the bottom.)
First, know what a cross section is. A cross section is the exposed shape or surface when a straight cut is made through a 3D figure. For example, if I make a cross section, or cut, through a sphere, the cross section will be a circle. The newly exposed surface is in the shape of a circle.
We want to know which 3D figures can make 2 different cross sections, parallel to the base, that are congruent. Congruent means same shape but different size. Parallel to the base means the cut is completely horizontal.
Here's a photo of Edge incase you're doubtful.