what solid will this lesson focus on?

a- rectangular solid
b- cone
c- regular square pyramid
d- triangular prism

The answer for the question shown above is the option C, which is: C- Regular square pyramid. 
 The explanation is shown below:
 By definition a regular square pyramid must be a pyramid with a square base, which means that the sides of its base have the same length. 
 You can identify it as a pyramid because it has an apex, a height, lateral faces that are congruent isosceles triangles and slant height (the altitute of the lateral faces).