How is the possessive formed if the noun is a possessive pronoun?

adding an -s without an apostrophe
adding an aspostrophe and an -s
adding an apostrophe and -es
adding nothing

The answer to the question above would be that if the noun is a possessive pronoun the possessive is formed by adding nothing. This is the case because the pronoun is already indicating possession. Adding any suffix would make the sentence ungrammatical and would also make it redundant because one element is already indicating possession.

answer: producers

explanation:

they are producers because the use photosynthesis to collect sunlight and make food for themselves which when a animal comes around and eats it it becomes a food chain