I would argue that the right answer is the C: He makes light of Romeo’s heartache. Romeo is so blindly and desperately in love with Rosaline that he is even willing to accept that his "tears turn to fires" and that his eyes, "transparent heretics," "be burnt for liars," if they have lied to him and made him believe that Rosaline is as beautiful as a swan, when she may be not. Not even the sun, which sees everything, "saw her match since first the world begun," says Romeo. For that reason, Benvolio, whose name suitably means "good-will," is trying to downplay his cousin's strong and almost harmful feelings for Rosaline and alleviate his heartache, and that's why he jokes about her face being closer to that of a crow than to that of a swan.