The correct answer is "Brutus decides to join the conspiracy against caesar because he fears that caesar will become ruthless once he has absolute power".
Explanation:
The central idea of the passage is that Brutus has no doubt that Caesar will be crowned king, but he doubts that Caesar will not be corrupted once he is given power, and by this he plans to assassinate him before he rises to power, as he puts "kill him in the shell" (II.i.33-34).
