7. If the base edge length and the side edge length of a regular pyramid are equal, then the pyramid must not be ( ).
A. Triangular pyramid
B. Square pyramid
C. Pentagonal pyramid
D. Hexagonal pyramid
7. If the base edge length and the side edge length of a regular hexagonal pyramid are equal, and the base edge length is equal to the radius of the base, then in the right triangle formed by the height, the base radius, and the side edge length of the regular hexagonal pyramid, the side edge length and the base radius are equal (i.e., the hypotenuse is equal to one of the legs), which is impossible, so the answer is D.