The correct answer is option 'A' - frictional force acts on it.

Explanation:

When we stop pedaling the bicycle, it eventually comes to a stop. This can be explained by the presence of frictional force acting on it.

1. Frictional force:
Friction is a force that opposes the relative motion between two surfaces in contact. In the case of a bicycle, the tires are in contact with the ground. When we pedal, the forward force generated by our legs overcomes the frictional force, allowing the bicycle to move forward. However, when we stop pedaling, the forward force is no longer present, but the frictional force continues to act in the opposite direction.

2. Balanced and unbalanced forces:
According to Newton's first law of motion, an object at rest will remain at rest or an object in motion will continue moving in a straight line at a constant speed unless acted upon by an external force. In the case of the bicycle, when we stop pedaling, there is no longer an unbalanced force acting on it. The force of gravity is balanced by the normal force exerted by the ground, and there is no other external force pushing or pulling the bicycle. Therefore, the bicycle will eventually come to a stop due to the frictional force opposing its motion.

3. Effects of frictional force:
Frictional force acts in the opposite direction to the motion of the bicycle and opposes its motion. As the bicycle slows down, the frictional force increases, reducing its speed further. Eventually, the frictional force becomes greater than the remaining forward momentum, causing the bicycle to come to a complete stop.

Conclusion:
In conclusion, when we stop pedaling the bicycle, it stops due to the presence of frictional force acting in the opposite direction to its motion. The frictional force gradually slows down the bicycle and brings it to a stop.

Correct answer should be option D not A. Can anyone explain why option A is the correct answer?