Answer: born in Pennsylvania in 1791 in sentence 1.
Step-by-step explanation:
An adjective is used to describe someone, somewhere or something. An adjective helps in modifying the nouns or pronouns in a given sentence.
Based on the information provided in the question, the group of words that function as an adjective will be "born in Pennsylvania in 1791 in sentence 1".
The group of words provide us with more information about James Buchanan. Therefore, the correct option is A.