Pentagon!!!
Improved Answer:-
It is D because all quadrilaterals have 4 vertices whereas:-
A has 6 vertices, B has 5 vertices and C has 8 vertices
Triangle Quadrilateral Pentagon Hexagon Heptagon Octagon Nonagon Decagon
Parallelogram Rectangle Square Kite Rhombus Pentagon Octagon Hexagon Polygon
Triangle, quadrilateral, Pentagon, hexagon, heptagon, octagon, nonagon, decagon, undecagon, and dodecagon
Some of them are: triangle, quadrilateral, pentagon, hexagon, heptagon, octagon, nonagon, decagon ..... etc
Triangle and decagon; Quadrilateral and enneagon/nonagon; Pentagon and octagon; Hexagon and heptagon.
Triangle Quadrilateral Pentagon Hexagon Heptagon Octagon Nonagon Decagon
Some of them are: triangle, quadrilateral, pentagon, hexagon, heptagon, octagon, nonagon, decagon ..... etc
Parallelogram Rectangle Square Kite Rhombus Pentagon Octagon Hexagon Polygon
Triangle Quadrilateral Pentagon Hexagon Heptagon Octagon Nonagon
Triangle, quadrilateral, Pentagon, hexagon, heptagon, octagon, nonagon, decagon, undecagon, and dodecagon
Some of them are: triangle, quadrilateral, pentagon, hexagon, heptagon, octagon, nonagon, decagon ..... etc
Octagon which has eight sides. The hexagon has six, while the pentagon has five.
No. An octagon has 8 vertices. A hexagon is the shape that has 6 vertices.
Triangle and decagon; Quadrilateral and enneagon/nonagon; Pentagon and octagon; Hexagon and heptagon.
It could be a triangle, a quadrilateral, a pentagon, a hexagon or even an octagon if they are two concave quadrilaterals.
pentagon Pentagon, nonagon octagon e.t.c.
Octagon.