Nuclear binding energy is necessary to overcome which of the following? einstein's mass defect
kinetic energy of the nucleus
repulsion of the protons
weak nuclear force

Nuclear binding energy is necessary to overcome EINSTEIN'S MASS DEFECT. Nuclear binding energy refers to the energy required to separate an atomic nucleus into its constituent elements, that is protons and electrons. The mass of a nucleus is always less than the sum of all its constituents. The difference is a measure of the nuclear binding energy which holds the nucleus together and it is called mass defect and can be calculated for using Einstein's formula for mass defect.

If its history of, then b) because a) implies only present day (now)

Is there any opitions? if you have the periodic table, the noble gases are 8a family, the halogen are the 7a family, and the nonmetal are  carbon, nitrogen, phosphorus, oxygen, sulfur, selenium, fluorine, chlorine, bromine, iodine and astatine.