Which airspeed is corrected for compressibility error?

Equivalent airspeed is the correct choice because it represents airspeed that has been corrected for both compressibility errors and for variations in air density. This adjustment is particularly crucial at higher altitudes or speeds, where the effects of compressibility become significant.

Indicated airspeed, on the other hand, is the readout from the airspeed indicator and does not account for altitude or temperature, and therefore it cannot be used for significant compressibility corrections. Calibrated airspeed is the indicated airspeed corrected for instrument and position error but still does not factor in compressibility error. True airspeed, while it provides the actual speed of the aircraft through the air considering altitude and temperature, also does not include corrections for compressibility.

Thus, equivalent airspeed is essential for accurate performance calculations at high speeds and altitudes and is designed specifically to address these factors, making it the most suitable answer to the question.