The correct statement that best explains what happens, based on Newton's First Law, is:
You keep moving forward because objects in motion stay in motion unless acted on by a force.
This statement accurately describes the principle of inertia, which states that an object in motion will remain in motion at a constant velocity unless acted upon by a net external force. In this scenario, when the car suddenly stops, you continue moving forward until the seatbelt exerts a force on you, stopping your forward motion.