When a bus moving at constant speed suddenly comes to a halt, passengers tend to pitch forward. What is the main reason for this observation?
a) An external force suddenly pulls the passengers forward when the brakes are applied.
b) The sudden braking reduces the friction between passengers and the seat, allowing them to slide forward.
c) Passengers tend to keep moving forward due to their inertia of motion.
d) The compressed air inside the bus pushes the passengers forward when the bus stops suddenly.