Which of the following element has highest binding energy per nucleon?

The correct answer is Option (1) → Fe

The binding energy per nucleon measures how tightly a nucleus is held together, and it is greatest for nuclei of mass number close to 56, which is iron.

Fe (A = 56) sits at the peak of the curve. He (A = 4) is a light nucleus and U (A = 238) a heavy one, so both lie below the peak, and Al (A = 27) is on the rising part of the curve just before it.

NCERT (2026-27):
Nuclear Binding Energy – “… (i) the binding energy per nucleon, E_bn, is practically constant, i.e. practically independent of the atomic number for nuclei of middle mass number ( 30 < A < 170). The curve has a maximum of about 8.75 MeV for A = 56 and has a value of 7.6 MeV for A = 238.”