NEED TO KNOW ASAP!!!

Read the excerpt from act 4, scene 3, of Julius Caesar.
BRUTUS. No man bears sorrow better. Portia is dead.
CASSIUS. Ha! Portia?
BRUTUS. She is dead.
CASSIUS. How scaped I killing when I crossed you so?
O insupportable and touching loss!
Upon what sickness?
BRUTUS. Impatient of my absence,
And grief that young Octavius with Mark Antony
Have made themselves so strong—for with her death
That tidings came. With this, she fell distraught,
And, her attendants absent, swallowed fire.
Why is this excerpt an example of situational irony?
O Portia died from her wounds the same night she cut
herself to prove her strength to her husband.
O Brutus does not believe that Portia is dead.
O Even though Brutus lied to protect her, he could not
save her life.
o Octavius and Mark Antony killed Portia.