The thing that is foreshadowed by the given lines is A. Mercutio’s death
<h3>What is Foreshadowing?</h3>
This refers to the literary technique of giving hints or clues about what will happen in the future.
Hence, we can see that from the given narration, the speaker talks about finding a grave man by this time tomorrow and this is a clear hint that Mercutio would die.
