Answer:
b. quadratic function
Explanation:
If a baseball player hits a home run, the function that best represent the height of the ball over time because this is a problem of projectile motion, a type of motion we get when an object is thrown near the Earth's surface, so it moves along a curved trajectory affected just by the action of gravity, if we ignore the air resistance. So that function follows the form:

Where:

As you can see, this function is a parabola that opens downward.