The correct answer is b) sulfide ion.
Explanation: In chemistry, anions are negatively charged ions. The S2 anion specifically refers to a sulfur ion that has gained two electrons, resulting in a -2 charge. This anion is commonly known as the sulfide ion. On the other hand, a sulfate ion (option a) is a different species, consisting of sulfur and oxygen with the formula SO4^2-. The sulfur ion (option c) typically refers to a neutral atom of sulfur, while sulfur ii ion (option d) is not a commonly used term. Therefore, the name for the S2 anion is indeed the sulfide ion.