What is the shape of the cross-section formed when a cone intersects a
plane as shown in the drawing?

A circle is formed when a cone intersects a plane.

Explanation:

A cross section is the process where a surface is shown when a straight cut is made by something. In the question  given when a cone is intersected by a plane horizontally the shape of the cross - section is a circle . On the other hand when the cone is intersected vertically by a plane the shape of the cross- section will be a triangle. Hence the shape of the cross section depends according to the cut.

Cross section is basically used to find what is there inside the object.

the minoan civilization flourished in the middle bronze age on the island of crete located in the eastern mediterranean from c. 2000 bce until c. 1500 bce. with their unique art and architecture, and the spread of their ideas through contact with other cultures across the aegean, the minoans made a significant contribution to the development of western european civilization as it is known today. labyrinth-like palace complexes, vivid frescoes depicting scenes such as bull-leaping and processions, fine gold jewelry, elegant stone vases, and pottery with vibrant decorations of marine life are all particular features of minoan crete.  

so basically their unique way of ding arts, as well as architecture.