Final answer:
The subject related to the given question is Projectile Motion.
Step-by-step explanation:
The subject related to the given question is Projectile Motion.
Projectile Motion refers to the motion of an object that is projected into the air and then moves along a curved path under the influence of gravity. In this case, the ball is thrown directly downward with an initial velocity of 9 m/s. When an object is thrown downward, it experiences a constant downward acceleration due to gravity, causing it to fall faster and faster.
Therefore, the correct answer is A) Projectile Motion.