A polygon is convex if, for every pair of points, $\text{P}$ and $\text{Q}$ belonging to the polygon, the line segment $\text{PQ}$ lies completely inside or on the polygon.

Which one of the following is $\underline{\text{NOT}}$ a convex polygon?

Option A is not a convex polygon as if we choose $\text{P}$ and $\text{Q}$ on the left-most tail the line segment $\text{PQ}$ will not be inside the polygon.