Answer: B. Vertex
Explanation:
Vertex of Parabola is a point of parabola that lies at the lowest point of U-shaped parabola.
It is basically the turning point of the directing of parabola.
We are given a U-shaped parabola in the picture.
The red dot is located at the minimum of the parabola.
That means the red dot indicates the vertex of the parabola.