Why did the romans change their government from a monarchy to a republic? a. rome had grown so large that a single monarch was unable to rule the entire country. b. the first king, romulus, made a law stating that after seven kings, the government must change. c. the plebeians revolted against the monarchy, dethroned the king, and changed the government. d. after 200 years of harsh rule by kings, the people wanted more of a role in government.