What led to the decline of the Roman Republic and the ultimate rise of dictator Julius Caesar? Select one: a. The republic did not place a big enough role on the military, which was too weak and susceptible to outside invaders. b. External threats, most notably the Carthaginians, invaded and conquered all of Rome, ending the Roman Republic. c. The power and wealth that expansion brought were too much for the republic to handle; political leaders fought and killed each other for control. d. Many living in conquered regions were unhappy with the republic and revolted against it.