Question

The atomic mass of an atom can be found by

Answer 1

A. Adding the number of protons and number of neutrons in the atom

Electrons are so incredibly small that the number of electrons makes almost no difference in the atomic mass. So b and c are not the answer.

D doesn't really make sense because like if you want to know the mass of a basket of apples and oranges, you'd add up the apples' and oranges' masses, not subtract.