Mass defect is associated with:

A. nuclear fusion

B. nuclear fission

C. radioactive decay

D. mass lost by nuclear collisions

B. Nuclear fission

Explanation:

Nuclear binding energy is used to determine whether fission or fusion will be a favorable process. The mass defect of a nucleus represents the mass of the energy binding the nucleus, and is the difference between the mass of a nucleus and the sum of the masses of the nucleons of which it is composed.