Read the excerpt from act 4, scene 3, of The Tragedy of Julius Caesar.

[BRUTUS.] Messala, I have here receivèd letters,
That young Octavius and Mark Antony
Come down upon us with a mighty power,
Bending their expedition toward Philippi.

MESSALA. Myself have letters of the selfsame tenor.

BRUTUS. With what addition?

MESSALA. That by proscription and bills of outlawry,
Octavius, Antony, and Lepidus
Have put to death an hundred senators.

BRUTUS. Therein our letters do not well agree.
Mine speak of seventy senators that died
By their proscriptions, Cicero being one.

CASSIUS. Cicero one!

MESSALA. Ay, Cicero is dead,
And by that order of proscription.

How does this interaction affect the plot?

It clarifies the relationship between Brutus and Mark Antony.
It informs the audience about events that took place off stage.
It provides background information about Brutus’s relationship with Messala.
It sets up a conflict between Brutus and Messala regarding the deaths of senators.