Choose the answer. Which best identifies a subplot in Julius Caesar and explains its significance?

Portia struggles to understand her husband's secrecy; it indicates that
Brutus's behavior is out of the ordinary.

Brutus and Cassius struggle with Antony and Octavius for control of Rome; it builds suspense about who will assume power next.

Brutus struggles with the decision to join the conspirators or not; it builds suspense about whether or not the assassination will occur.
Brutus struggles with Calpurnia over whether they should inform Caesar of the assassination plot; it builds suspense about who can and cannot be trusted.