One mole of
consist of three atoms of sodium, one atom of phosphorus and four atoms of oxygen.
Now, according to question four moles of
is present. Therefore, every element present in the compound is multilply by four with their number of atoms in the compound.
So, Number of atoms of sodium in four moles of
is
= 12 atoms of sodium.
Number of atoms of phosphorus in four moles of
is
= 4 atoms of phosphorus.
Number of atoms of oxygen in four moles of
is
= 16 atoms of oxygen.
Hence, number of atoms of sodium is 12 , number of atoms of phosphorus is 4 and number of atoms of oxygen is 16
Thus, option (D) is the correct answer.