Brutus' agreement to worries
a. allow antony to speak at the funeral, cassius.
b. lead the republic, antony.
c. end cimber's brother's banishment, cassius.
d. bathe his hands in caesar's blood, the people.

The answer is A. Allow Antony to speak at the funeral, Cassius

they think that killing Caesar was a necessary sacrifice, but Brutus know that Antony and Caesar were really close and he thought that allowing Antony to speak at the funeral is the right thing to do.

Of course this worry Cassius, because Brutus just about to give a speech about how is it necessary to kill Caesar in front of his best friend

The dethroned emperor!