The following are correct: B & C
B) He agrees to perform the marriage of Romeo and Juliet as soon as possible.
Text Ev:
In one respect I'll thy assistant be;
For this alliance may so happy prove
To turn your households’ rancour to pure love. (p.47)
C) He is concerned that Romeo May forget Juliet as quickly as he forgot Rosaline.
Text Ev:
Holy Saint Francis! What a change is here!
Is Rosaline, that thou didst love so dear,
So soon forsaken? Young men's love then lies
Not truly in their hearts, but in their eyes. (enotes etext p. 46)