How do the conflicts between octavius and mark antony as well as brutus and cassius in act 4 of the tragedy of julius caesar develop the play’s plot?

octavius and mark antony’s conflict foreshadows future disagreement regarding rome’s leadership; brutus and cassius’ conflict shows the difference in values as well as the deterioration of the republic’s ideal of friendship.
octavius and mark antony’s conflict shows the breakdown of their strong friendship; brutus and cassius’ conflict shows their similar values and how that can strengthen the republic’s ideal of friendship.
octavius and mark antony’s conflict shows the great success enjoyed by rome after caesar’s death; brutus and cassius’ conflict foreshadows future disagreement regarding rome’s leadership.
their conflicts do not develop the plot.