The correct option is
C ParameciumA trichocyst is an organelle found in certain ciliates and dinoflagellates. Mucoid trichocysts are elongated inclusions that may be ejected as visible bodies after artificial stimulation. Filamentous trichocysts in Paramecium and other ciliates are discharged as filaments composed of a cross-striated shaft and a tip.
So, the correct answer is 'Paramecium'