Answer:
Octagonal pyramid
Explanation:
Hexagonal Prism: 8 faces
2 hexagon bases, and 6 faces that connect each side of the bases
Octagonal pyramid: 9 faces
One octagon base, and 8 faces that meet at a point- all extending from each side of the base
Rectangular prism: 6 faces
Two rectangle bases, and 4 faces connecting each side of the bases
Pentagonal pyramid: 6 faces
One pentagon base, and 5 faces that meet at a point- all extending from each side of the base
I recommend searching for a picture of each of the figures to help you understand this.