The correct answer is C) The flow of liquid is developed by imparting energy due to the rotation of an impeller. This is correct because the defining characteristic of a centrifugal pump is that it uses the rotation of an impeller to create a pressure differential that draws in fluid and propels it through the discharge. The impeller's rotation imparts kinetic energy to the fluid, which is then converted to pressure energy as the fluid exits the pump. The other answer choices are incorrect because: A) Centrifugal pumps can be mounted in either horizontal or vertical orientations; B) Centrifugal pumps should be started with the discharge valve partially closed to avoid overloading the motor; and D) Centrifugal pumps are not well-suited for high viscosity fluids, which are better handled by positive displacement pumps.