D

Step 1: Understand the forces at play when an object moves in a circular path. When the cyclist bends inwards, they are adjusting their body position to maintain balance and counteract the centrifugal force acting outward due to the circular motion.
Step 2: In a cyclist, the body leans into the turn, and their contact with the bicycle helps them exert a force towards the center of the circular path. This helps them maintain balance.
Step 3: In contrast, a car passenger does not have control over the car and is merely a passenger; instead, they are subject to the centrifugal force. If the car turns sharply, the passenger can end up being thrown outward because they are unable to lean into the turn like a cyclist.
Step 4: The centrifugal force acts on the passenger, and unless they brace themselves or hold onto something, they may become unbalanced and get thrown outwards.
Conclusion: Therefore, the main reason is that the cyclist has to counteract the centrifugal force actively while the passenger in the car is just carried along, leading them to be thrown outward if not properly secured.
Therefore, the correct answer is D.