An Ion Is Formed

An ion is formed
I. by either adding protons to or subtracting protons from the atom.
II. by either adding electrons to or subtracting electrons from the atom.
III. by either adding neutrons to or subtracting neutrons from the atom.

A) Only I is true.
B) Only II is true.
C) Only III is true.
D) All of the statements are true.
E) Two of the statements are true.