According to Newton’s second law, the relationship between force, mass, and acceleration is given by the formula \( F = ma \), where \( F \) is the force, \( m \) is the mass, and \( a \) is the acceleration. If the force (provided by the motor) remains constant and the mass of the rocket increases, the acceleration will decrease.
Therefore, the correct response is:
As rocket mass increases, acceleration decreases.