The mass of a substance is the mass per mole of its entities, where the term entities can describe

            The molar mass of a substance is the mass per mole of its entities, where the term entities can describe atoms, molecules, ions or formula units.

Explanation:

                  Molar mass is the mass of any compound divided by mole. Means, if any chemical is given a specific molar mass it means this mass is being given by 6.022 × 10²³ entities of that chemical.

                  The molar mass of any compound is calculated by adding up the atomic masses of all atoms present in that chemical.

Example:

Molar Mass of H₂ =  1.008 + 1.008  =  2.016 g/mol

Molar Mass of NaOH  =  23 + 16 + 1  =  40 g/mol

Molar Mass of HCl =  1 + 35.5  =  36.5 g/mol

b) mutualism

hope this : )

the answer is c i believe