Which line of dialogue from Act III, scene i of Romeo and Juliet most foreshadows that Mercutio’s death will lead to other tragic events in the story?

Question

Benvolio: O Romeo, Romeo! brave Mercutio’s dead;
That gallant spirit hath aspir’d the clouds,
Romeo: This day’s black fate on more days doth depend;
This but begins the woe others must end.
Tybalt: Thou wretched boy, that didst consort him here,
Shalt with him hence.
Prince: Romeo slew him, he slew Mercutio;
Who now the price of his dear blood doth owe?

Answer 1

The line that most foreshadows that Mercutio’s death will lead to other tragic events is spoken by Romeo:

"This day’s black fate on more days doth depend;
This but begins the woe others must end."

This line suggests that the consequences of the day's events will have a lasting impact and lead to further tragedy.