The acceleration of an object depends upon

Net force and Mass

Explanation:

The acceleration of an object is dependent upon two variables - the net force acting upon the object and the mass of the object.

I think the correct answer from the choices listed above is the first option. The Curies conclude about radioactivity based on their studies that the amount of radioactivity is an extensive property because it varies as the amount of material varies. Hope this answer the question. Have a nice day.