What geometric term does a first baseline, home plate, and a third baseline of a baseball field represent?

The first baseline, home plate, and the third baseline of a baseball field represents angles.

Th first and third baselines intersect at home plate.

So, home plate is the vertex of an angle.

Vertex typically means a corner or a point where lines meet. For example a square has four corners, each is called a vertex.

the answer is b