Question

a first law of motion
b second law of motion
c third law of motion
d law of gravitation

Explanation:

Newton's third law of motion states that for every action, there is an equal and opposite reaction. In the case of the balloon car, when the gas is released from the balloon (action), the car moves in the opposite direction (reaction). This is a direct application of Newton's third law.

Answer:

B. second law of motion