<prompt> Auxotonic contraction of a muscle is:Same as isotonic contraction for different lengths of fibresBased on the principle of recruitment of motor unitsCombination of isometric isotonic contractionsDynamic followed by adynamic contraction  <response>: Auxotonic contraction: is the one in which the strength of contraction goes increasing, as the contraction proceeds. This phenomenon is about a single contraction. As the contraction proceeds, more and more motor units may be recruited in the contraction, thus increasing the strength of contraction.This is in skeletal muscle. Staircase phenomenon: is phenomenon for multiple contractions;in which the strength of contraction goes increasing in successive contractions. 