What is the average mass of a proton or a neutron

Average mass of proton is 1.007276 u  and that of neutron is 1.008664 u  

Explanation:

There are 3 subatomic particles present in an atom. They are: protons, electrons and neutrons.

Mass of electron is almost negligible as compared to the mass of proton and neutron.

Masses of the subatomic particles:

Mass of protons = 1.007276 u

Mass of neutrons = 1.008664 u  

Mass of electrons = 0.00054858 u

Hence, average mass of proton is 1.007276 u  and that of neutron is 1.008664 u  

i think it's letter a.