The constancy of the binding energy per nucleons in the range 30 < A < 170, where A is the mass number shows that:

Nuclear force is short ranged

The constancy of the binding energy in the range 30 < A < 170 is a consequence of the fact that the nuclear force is short-ranged. A very heavy nucleus, say A = 240, has lower binding energy per nucleon compared to that of a nucleus with A = 120.

The correct answer is Option (2) → Nuclear force is short ranged