Final answer:
The statement 'The standing army is only an arm of the standing government' is a metaphor, signifying that the armed forces are a part of and controlled by the government. It is not a paradox or an allusion. The correct answer is option C.
Step-by-step explanation:
The phrase "The standing army is only an arm of the standing government" is a metaphor. In this context, the standing army is being compared to a part of a larger entity, which is the government. This metaphor illustrates the idea that the armed forces are a component of the government's structure and capabilities, much like an arm is a part of the human body, implicating that the military's actions and existence depend on governmental control and decisions. This expression does not fit the definition of a paradox, which is a statement that contradicts itself and still might be true, nor an allusion, which is an indirect reference to something.