Correct Answer: mass

Solution : The correct answer is mass.

According to the second law of motion formulated by Isaac Newton, for a given force, acceleration is inversely proportional to the mass of the object. This relationship is described by the equation F = ma , where 'F' is the force applied to an object, 'm' is the mass of the object and 'a' is the acceleration produced. As per this equation, when force remains constant, if the mass of an object increases, the acceleration will decrease and vice versa.