The most stable elements have an atomic number above 92.

a. a high proton to neutron ratio.

b. a high binding energy per nucleon.

c. a low binding energy per nucleon

Answer: b) high binding energy per nucleon

Explanation: Most elements become unstable as their atomic numbers reach/pass the special 92 number. This is due to the imbalance between neutrons and protons in their nucleus. As the number of protons and neutrons increases, the neutron-proton ratio in the nucleus has to increase to offset any instability in the nucleus.

The binding energy per nucleon of an element is the amount of energy required to disassemble the nucleus of an atom into its fundamental components (protons & neutrons). A high binding energy indicates serious difficulties in disassembling an atom's nucleus. Meaning the atom is very stable as the energy to cause it to decompose radioactively is too high.

So, an atom with atomic number higher than 92 would be stable if it has a high binding energy per nucleon.