C. The three-branch system established a strong central government without giving too much power to any one group.
The colonists were used to a strong central government, like England's, but they were afraid of tyranny, like with England. Once they had independence, they created a strong government because it was their custom, but they instituted a system of checks and balances (with three branches) to prevent any one person or group of people from gaining too much power.
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