Assertion:  If a heavy nucleus is split into two medium-sized parts, each of the nuclei will have more binding energy per nucleon than the original nucleus. 

Reason:  Joining two light nuclei together to give a single nucleus of medium size means more binding energy per nucleon than the two nucleus.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false.

• If both assertion and reason are false.