The mass of a nucleus can be either less than or more than the sum of the masses of nucleons present in it.
The whole mass of the atom is considered in the nucleus.
A. If both assertion and reason are true and the reason is the correct explanation of the assertion
B. If both assertion and reason are true but reason is not the correct explanation of the assertion
C. If assertion is true but reason is false.
D. If assertion is false but reason is true
