A deuterium (an isotope of hydrogen) nucleus (mass = 2.01355 amu) is made up of one proton (mass = 1.007276 amu) and one neutron (mass = 1.008665 amu). Which statement best describes what happens when a deuterium nucleus breaks apart?

A. The mass decreases and energy is released.

B. The mass increases and energy is absorbed.

C. The mass increases and energy is released.

D. The mass decreases and energy is absorbed.