What is molar mass used to convert between?

Molar mass used to convert between the "mass to the moles"

Explanation:

The molar mass of a compound is the the mass of the sample of the compound used divided by the amount of the substance in the sample. This is measured in moles. The base unit for the molar mass is the kg/mol.  From mass to moles can be converted through molar mass. By  analyzing the relationship between the molar mass, moles and particles, dimensional conversion can take place between mass, number of moles and number of atoms.

the correct option is c.

isotopes refers to different forms of the same element with the same atomic number but different mass number as a result of difference in their neutron numbers. isotopes have different relative atomic mass but share the same chemical properties.