Which of the following best describes a cone?
a. a three-dimensional solid made from two parallel and congruent discs not in the same plane and all the points between them
b. a three-dimensional solid made from a pile of similar two-dimensional circles that grow smaller as the solid gets taller until it reaches a point at the vertex
c. a three-dimensional solid consisting of a base, a point not in the same plane as the base, and all the points between them
d. a three-dimensional solid consisting of two parallel congruent polygons and all the points between them