Dear Student
Answer to your question is Force. This is because of newton's 2nd law of motion, which state that F = m x a , where F is force, m is mass of an object, and a is acceleration of an object.
F = m x a can be written as a = F/ m. Therefore, we can conclude that acceleration of an object is directly proportional to magnitude of force and inversely proportional to mass of an object.
Regards