I think it is D) but I'm not quite sure. Thanks in advance!

Right after the ball is thrown at angle of 45 deg, the acceleration is

a)g

b)sin(45) * g

c)cos(45) * g

d)tan(45) * g

To determine the acceleration right after the ball is thrown at an angle of 45 degrees, we can break down the initial velocity into its horizontal and vertical components.

The horizontal component of the velocity remains constant throughout the motion, since there is no horizontal acceleration. On the other hand, the vertical component is subject to the acceleration due to gravity, which is directed downwards.

The initial vertical velocity can be determined using the angle and the initial overall velocity, assuming the initial overall velocity is represented by "v". In this case, the initial vertical velocity can be calculated as v * sin(45°).

Since the only vertical force acting on the ball is gravity, the initial vertical acceleration is equal to the acceleration due to gravity (g), directed downwards.

Therefore, the correct answer is b) sin(45°) * g. This is because sin(45°) represents the ratio between the vertical component of the velocity (v * sin(45°)) and the initial overall velocity, giving us the correct magnitude of the initial vertical acceleration.