Consider the anion whose charge is 2- and whose electron configuration is identical to argon. what is the symbol for this anion

If the ion is negatively charged, anion, it means that it gains two electrons from its surroundings. The number of electrons of an argon (neutral atom) is 18. Two of the electrons in our anion is from the surrounding, so originally it only has 16 electrons.

In the periodic table, the 16th element is sulphur. The chemical symbol of sulphur is S. Thus, the anion is the negatively charged sulphur with chemical symbol of S2-. 

i think it's letter a.