Answer:
B. Marginal cost equals long-run average total cost.
Explanation:
The zero profit condition implies that entry continues until all firms are producing at minimum long run average total cost. Since the marginal cost curve cuts the long run average total cost curve at its minimum point, marginal cost and long run average total cost must be equal in long run equilibrium.
When the ball starts its motion from the ground, its potential energy is zero, so all its mechanical energy is kinetic energy of the motion:

where m is the ball's mass and v its initial velocity, 20 m/s.
When the ball reaches its maximum height, h, its velocity is zero, so its mechanical energy is just gravitational potential energy:

for the law of conservation of energy, the initial mechanical energy must be equal to the final mechanical energy, so we have

From which we find the maximum height of the ball:

Therefore, the answer is
yes, the ball will reach the top of the tree.