Mercutio is romeos sword fighting BFF he never backs down from a duel, Though he is neither a Montague or a Capulet, he gets himself into a long lasting family feud. Tybalt kills him in act 3, scene 1. So the answer would would be a. Best friends.
The reason someone would add more lines to Romeo and Juliet's death would be to make it more dramatic and interesting. Therefore more people would be interested and read it.
