The dependence of the critical temperature for superconductivity upon
(A) Isotopic mass
(B) Isotonic mass
(C) Isobaric mass
(D) Both A and B

Hint: We know that Isotopes are variants of a particular chemical element which differ in neutron number, and consequently in nucleon number. All isotopes of a given element have the same number of protons but different numbers of neutrons in each atom. Isotopes are simply atoms with more neutrons; they were either formed that way, enriched with neutrons sometime during their life, or are originated from nuclear processes that alter atomic nuclei. So, they form like all other atoms. Radioactive isotopes are not always dangerous, though. Some only give off tiny amounts of radiation. There are radioactive isotopes in nature all around us. Most of them cause us little or no harm.

Complete step-by step answer:

We know that the critical temperature of a substance is the temperature at and above which vapor of the substance cannot be liquefied, no matter how much pressure is applied. Every substance has a critical temperature. Above the critical temperature, the molecules have too much kinetic energy for the intermolecular attractive forces to hold them together in a separate liquid phase. Instead, the substance forms a single phase that completely occupies the volume of the container.
$\alpha =\dfrac{M}{\Delta M}\times \dfrac{\Delta {{T}_{c}}}{{{T}_{c}}}$
Where $\alpha$= isotopic co-efficient
$\Delta M=M-{{M}^{*}}$ is the difference in the isotopic masses.
${{T}_{c}}=$ critical temperature of superconductor
$\Delta {{T}_{c}}=$change in critical temperature
Clearly critical temperature depends on the isotopic mass.

Hence, the correct answer is A.

Note: We know that the relative isotopic mass is a unitless quantity with respect to some standard mass quantity. The relative atomic mass can be taken as the weighted mean mass of an atom of an element compared to the mass of 1/12 of the mass of an atom in C-12. Mass numbers are always whole numbers with no units. Also, relative isotopic mass is not the same as isotopic mass, and relative atomic mass which is also called atomic weight is not the same as atomic mass.
It should also be known to us that substances that expand at the same rate in every direction are called isotropic. For isotropic materials, the area and volumetric thermal expansion coefficient are, respectively, approximately twice and three times larger than the linear thermal expansion coefficient.