Step-by-step explanation:
The correct answer is (b) What distinguishes a plural common noun from a singular possessive noun is an apostrophe after the S.
When forming the possessive form of a singular noun, the apostrophe is placed before the "s" (e.g., "dog's bone"). For plural nouns that end in "s," the apostrophe is placed after the "s" (e.g., "dogs' bones"). This helps to distinguish between a plural common noun and a singular possessive noun.