How does the shape of the parabola change when you move the focus toward the vertex? a. it becomes more narrow c. it doesn't change b. it becomes wider

a. It becomes more narrow.

Explanation:

Refer to the diagram shown below.

Suppose that the focus of the parabola is 2a units from the vertex. Then the distance from the vertex to the directrix is also 2a.
Let 2b = the distance from the focus to a point located horizontally from the focus. Then the distance from the point to the directrix will also be 2b.

When the focus moves closer to the vertex so that the distance between them is a, then the directrix also moves closer to the vertex.
Accordingly, the curve narrows so that the distance from the focus to a point located from the focus.is b as shown in the diagram.