Answer:
a. pentagon
b. triangle (scalene or isosceles)
Explanation:
You want a description of the horizontal and vertical cross sections of a right pentagonal pyramid.
Horizontal cross section
The cross section of any right pyramid parallel to the base is similar to the shape of the base of the pyramid. This means the horizontal cross section of a pentagonal pyramid is a pentagon.
Vertical cross section
The precise shape of the vertical cross section through the top of the pyramid will depend on its orientation with respect to the vertices of the base. The outline of the top figure in the attachment shows the scalene triangle that results when the cross section is made through one of the slant edges.
If the vertical cross section is taken parallel to an edge of the base, the result will be an isosceles triangle.