The correct option is C cation
Ionic species with a positive charge are called cations.
Cations form when an element or group of elements(compounds) lose one or more electrons. Cations can be formed from metal elements, as well as nonmetal elements. If a metal element forms an ion, it always forms a cation. Some metals always form the same type of cation. For example, sodium always forms a +1 cation (Na+) and magnesium always forms a +2 cation (Mg2+).