This question is incomplete, here´s the complete question.
The sentence below is missing at least one apostrophe. Add the apostrophe where needed.
Cows manure is used as fertilizer on farms all across America.
Answer: Cow´s manure is used as fertilizer on farms all across America.
Explanation:
The apostrophe is used for two very different purposes: contractions and possession.
Contractions are the most frequent use of apostrophes. We know there´s a contraction when a noun or pronoun is merged with a verb, and the apostrophe often substitutes a dropped letter. For example: "She's shy."
In this case (cow´s) the apostrophe is a possessive one. Another example would be: "The doctor's patient"
