You are correct, the answer A) One set of rotating blades, one set of stationary vanes is the correct representation of an axial compressor stage. In an axial compressor, the air flow is directed parallel to the axis of rotation. The rotating blades, also called the rotor, impart energy to the air and increase its pressure and velocity. The stationary vanes, also called the stator, then redirect the air flow and convert the kinetic energy into static pressure. This alternating arrangement of rotating blades and stationary vanes is the defining characteristic of an axial compressor stage. The other options are incorrect because they do not accurately depict the configuration of an axial compressor stage. Option B has the order reversed, option C has an extra set of stationary vanes, and option D describes a different type of compressor configuration.