The correct answer is A. stubborn.
Words can have a denotation and a connotation. Denotation is the literal meaning of the word - what you would find in a dictionary if you looked the word up. On the other hand, connotation has to do with personal feelings and emotions one get when he or she thinks about a particular word.
Words such as grateful, proud, and honored tend to have positive connotations - people usually see them in a positive light. On the other hand, when someone is stubborn, that is usually a negative thing.