What is the term given to the condition in which cyclic pressure changes result in a repetitive failure and recovery of compressor air flow?

Correct Answer: Option D — Surge.

Surge is a complete breakdown of compressor flow characterized by violent, cyclic pressure oscillations. Unlike a localized stall, surge involves the entire compressor and can cause reverse flow, leading to severe mechanical stress and potential damage to the engine's internal components. It represents a critical failure of the aerodynamic stability.