Answer: The correct answer is - Lose electrons.
An ion is an electrically charged particle that is formed by either loss of electron or gain of electron from a neutral atom.
The atomic number of sodium is 11. It electronic configuration is- 2, 8, 1
In order to achieve stable electronic configuration, it loses one electron from its valence shell and becomes positively charged ion that is cation.
Thus, to form sodium ion ( which is a cation), loss of one electron takes place.