Mercutio can be seen as a foil to Romeo because his personality contrasts with Romeo's, thus emphasizing
Romeo's traits. At which point in the excerpted scene from Act 3 is this best illustrated?

A. when Romeo comforts Mercutio after he has been wounded
B. when Romeo takes revenge for the death of Mercutio by killing Tybalt
C. when Mercutio calls for a plague on the houses of Montague and Capulet
D. when Mercutio insists on fighting Tybalt while Romeo wants to walk away