if we look at the definition of preposition it is "a word governing, and usually preceding, a noun or pronoun and expressing a relation to another word or element in the clause, as in “the man on the platform,” “she arrived after dinner,” “what did you do it for ?" its like the sentence we are dealing with right now "two days jumped after the two boys"
A. their Their refers to the the multiple (both means more than one) squirrels themselves If it was HIS then it would refer to only one squirrel If it was OUR it would mean you and me (We) had our acorns hidden
