Step 1: Concept
Reciprocating pumps (like piston or plunger pumps) produce a pulsating flow because they deliver liquid in "bursts" during each stroke.
Step 2: Meaning
Pulsation can cause uneven chemical application and vibration damage to hoses.
Step 3: Analysis
An air chamber is a small tank containing trapped air. As the pump pushes liquid, the air compresses, acting as a cushion (accumulator) that releases the pressure steadily during the pump's return stroke.
Step 4: Conclusion
This creates a smooth, continuous flow at the nozzle.
Final Answer: (D)