I think the third option would be a suitable answer.
It is protected by the fact that it has a system of separation of powers with three branches that control each other and prevent tyrannical behavior from a single branch. They are also separated into local provinces and autonomous regions that are ruled by small scale governments that have some degree of independence and that could easily oppose a new form of tyrannical government.
I think more men and more powerful weapons
B, European settlers were immune to such diseases like smallpox because it came from their region, when knowledge that the native Americans were not immune and the disease was lethal to them, they started distributing blankets and clothing items that were infected with the viruses and caused a major impact on native population
