<prompt> Which of the following show regressive metamorphosis -Hydatid cystCysticercoidCysticercus bovisCysticercus cellulosae  <response>: Retrogressive metamorphosis is when an organism changes from a more advanced form to a primitive one.the ruptured hydatid cyst releases protoscolices into tissues which do not develop into adult forms according to law of migration of cestodes... but they form a new hydatid tissue against the law... this is called regressive metamorphosis. 