What is the molar mass of calcium phosphate?

The molar mass of any chemical compound is the ratio of the mass of a sample of that compound to the amount of substance in that sample (in moles). The molar mass is a bulk property of a material rather than a molecular property. The molar mass is commonly expressed as $gmo{l}^{-1}$.

The molar mass of any compound may be calculated by summing the relative atomic masses of each element present. The chemical formula of a molecule can be used to calculate the number of atoms.
Let us now compute the molar mass of the given chemical, calcium phosphate. Calcium phosphate's molecular or chemical formula is ${\mathrm{Ca}}_3{\left({\mathrm{PO}}_4\right)}_2$ or ${\mathrm{Ca}}_3{\mathrm{O}}_8{\mathrm{P}}_2$. We already know the atomic mass of calcium, phosphorus, and oxygen which is mentioned below:
$Ca=40.078u$
$O=15.9994u$
$P=30.9737u$
From the chemical formula, it is clear that calcium phosphate comprises of three atoms of calcium, two atoms of phosphorus,s and eight atoms of oxygen and thus the  molar mass of this compound can be easily calculated by adding the mass of three calcium atoms, two phosphorus atoms and eight oxygen atom as shown below:
$\text{ Molar mass of }{\mathrm{Ca}}_3{\left({\mathrm{PO}}_4\right)}_2=(3\times \mathrm{Ca})+(2\times \mathrm{P})+(8\times \mathrm{O})$
$=(3\times 40.078)+(2\times 30.9737)+(8\times 15.9994)=310.1766{\mathrm{gmol}}^{-1}$

Hence, the correct answer is option A.