Which of the Following Statements About Atoms Is True

Which of the following statements about atoms is true?

A) The negative charge of an electron is larger than the positive charge of a proton. This is the reason that there are usually more protons than electrons in an atom.
B) Neutrons add mass to an atom without influencing other properties.
C) When the number of protons equals the number of electrons, an atom has a neutral charge.
D) Atoms of an element are radioactive whenever they vary in their number of neutrons.
E) The energy level of electrons is higher in shells close to the nucleus.