[A]. In a two stage reciprocating air compressor with complete intercooling, maximum work is saved.
[B]. The minimum work required for a two stage reciprocating air compressor is double the work required for each stage.
[C]. The ratio of the volume of free air delivery per stroke to the swept volume of the piston is called volumetric efficiency.
[D]. none of the above
✅ The correct answer is option D.