Answer:
C) gravity and inertia
Step-by-step explanation:
- Inertia affects the motion on the horizontal axis. In fact, there are no forces acting on the projectile along the horizontal direction: therefore, the projectile will continue its motion with constant velocity for inertia.
- Gravity affects the motion on the vertical axis: in fact, there is only one force acting on the projectile along the vertical direction (gravity, which points downward), so along this direction the motion is uniformly accelerated, with constant acceleration g=9.8 m/s^2 towards the ground.