Final answer:
Among the options given, Brunei would most likely use a curfew to prevent clashes between citizens and its police force due to its absolute monarchy and restrictions on speech and assembly.
Step-by-step explanation:
The country that would most likely use a curfew to prevent clashes between citizens and its police force, among the options listed, would be Brunei.
Canada and the United States, being democratic nations, tend to use curfews less frequently and typically only in extreme circumstances, such as large-scale protests or riots. South Korea, while having a history of authoritarianism, has evolved into a democratic state with good relationships with the United States, embracing democracy and a market-oriented economy.
Brunei, in contrast, is an absolute monarchy where the Sultan has nearly total power over state affairs. This form of governance is more likely to employ curfews to maintain control and prevent disturbances, including potential clashes between citizens and police, especially considering Brunei's restrictions on speech and assembly.