D

Step 1: When a ball is thrown at an angle, its kinetic energy (KE) is influenced by both its vertical and horizontal motions.
Step 2: As the ball travels in the trajectory, its velocity has components in both the vertical and horizontal directions.
Step 3: The kinetic energy can be represented as KE = \frac{1}{2}mv^2, and as the ball goes up, it loses kinetic energy while gaining potential energy, especially at maximum height.
Step 4: The relationship between kinetic energy and horizontal displacement will typically follow a curved path where KE is maximized at the beginning and decreases as potential energy increases.
Therefore, the graph depicting a maximum at the start and decreasing towards equilibrium in option D would be the correct representation.