What is the correct form of the possessive for the chairman?

The possessive form of "chairman" is constructed by adding an apostrophe and the letter "s" at the end of the word, resulting in "chairman's." This construction indicates that something belongs to or is associated with the chairman. For instance, one might refer to the "chairman's report" or the "chairman's decision."

The other options do not follow the standard rules of forming possessives in English. Simply using "chairman" does not indicate possession. "Chairmans" incorrectly attempts to form a plural rather than a possessive, while "chairmens" is not a recognized form in English, as the plural of "chairman" is actually "chairmen." Thus, "chairman's" is the only grammatically correct choice for expressing possession.