Answer:
The correct answer is option A.
Explanation:
[tex]6Ca+4PO_4\rightarrow 2Ca_3(PO_4)_2[/tex]
Number of molecules of [tex]Ca_3(PO_4)_2[/tex] =2
In 1 molecule [tex]Ca_3(PO_4)_2[/tex] , there are 8 oxygen atoms:
[tex]4\times 2 = 8 [/tex]oxygen atoms.
Then 2 molecules of [tex]Ca_3(PO_4)_2[/tex] :
[tex]2\times 8 = 16[/tex] oxygen atoms.
Hence, the correct answer is option A.