Final answer:
The correct answer is 'External Function' as it pertains to a government's efforts to protect its citizens from threats outside its borders through measures such as military defense or intelligence services.
Step-by-step explanation:
The question references the actions that a government takes to protect its citizens, specifically in the context of ancient Chinese emperors and contemporary intelligence and counterintelligence services. When considering the options provided (Internal Customers, External Customers, External Function, Internal Functions), the correct answer reflects an external function of a government. Here, external function pertains to the actions taken by a government to ensure the safety of its citizens from threats beyond its borders, such as using military defense mechanisms like the Great Wall of China, or employing intelligence services to counter external threats.
Internal functions, in contrast, may involve domestic policies and administrative actions conducted within the government to maintain order and provide services to the inhabitants of the state, which would include using counterintelligence services to protect against internal threats.