Which of the following is included in nuclide symbols, but is not strictly necessary for the identification of the nuclide? a. mass number
b. atomic number
c. isotope number
d. none of the above

c. isotope number

Explanation:

Mass Number is the sum total of mass of protons and neutrons present in the nucleus of an atom.  Generally they are being used in distinguishing isotopes. E.g Carbon - 12, Carbon - 13

Atomic Number is the number of protons. Every single element has it's unique atomic number and can be used in identification purpose. E.g Carbon - 6, Hydrogen - 1.

The correct option is option C. This is the symbol that is not necessary for the identification of a nuclide.