<prompt> The clearance of drug meansVolume of plasma which is cleared of drug in unit of timeAmount of drug excreted in urineAmount of drug metabolized in unit of timeAll of the above  <response>: Clearance of a substance is the volume of plasma cleared of the substance in unit time ie in one minute. REF: TEXTBOOK OF MEDICAL PHYSIOLOGY GEETHA N 2 EDITION, PAGE NO - 353 