If 1 Mol of Oxygen-16 Were Formed from Protons and Neutrons,0.1366

If 1 mol of oxygen-16 were formed from protons and neutrons,0.1366 g of mass would be lost.What can best account for this loss?

A) Converting from the atomic scale (in atomic mass units) to the macroscopic scale (in grams) can often cause minor errors to occur.
B) The process was so exothermic that the system lost energy,which means that it also lost mass.
C) This is impossible because of the law of conservation of matter (so mass must be conserved) .
D) When fission occurs,the nuclei remaining always have a smaller mass.
E) Both a and c are correct.