Final answer:
The cell body of a neuron, also known as the soma, typically does not compose a majority of the neuron's volume and is quite compact; therefore option C (10% of the cell volume) is the closest approximation among the given choices.
Step-by-step explanation:
The cell body, also known as the soma, is a component of a neuron that houses the nucleus along with other organelles necessary for cell function. Considering its function as the neuron's 'control center,' it contains essential cellular machinery, but it usually does not compose a majority of the neuron's volume. Neurons can vary in shape and size, and the cell body's proportion to the entire neuron can differ based on neuron type. However, the cell body is typically quite compact, indicating that option A (90% of the cell volume) and option B (50% of the cell volume) are unlikely. Option D, which states that the cell body is found in the same position on every neuron, is not accurate since different types of neurons can have different configurations. Therefore, C (10% of the cell volume) would be the closest approximation among the given choices.