Hey!
ANSWER:
The Romans chose a republic as their form of government to keep any one person from gaining too much power.
REASON:
Before the decision was made to have a republic there was a Roman king that abused his high power. He used his higher authority to get away with crimes, such as non consensual intercourse. He was later forbidden to return, and the changed the rules of allowing any one person to rule.
Hope this helps!
- Lindsey Frazier ♥