Although the sentences are not stated in the question, you should look for sentences that use the possessive form. To form a possessive you should add apostrophe + s to the noun, that indicates the relationship of beloging between the noun and the next word in the sentence. Typically the correct answer for the particular question is "Julie's and Michelle's flowers were red, yellow, and blue". As it could be notice the form "Julie + apostrophe + s" and "Michelle + apostrophe + s" indicate that Julie and Michelle own the flowers.
