The pass of an electron is

A

Explanation:

The mass of an electron is equal to the mass of a neutron

Protons and neutrons have approximately the same mass, but they are both much more massive than electrons (approximately 2,000 times as massive as an electron). The positive charge on a proton is equal in magnitude to the negative charge on an electron.

a. equal to the mass of the proton and the neutron

Explanation:

but there is no

i guess you forgot putting it.