During its life-cycle ,Fasciola  hepatica(liver fluck)infects its intermediate host and primary host at  the following larval stages respectively:-
a) Redia and miracidium
b) Cercaria and redia
c) Metacercaria and cercaria
​d) Miracidium and metacercaria


 

Dear student,
Answer is d). Miracidium and metacercaria
​The intermediate host of liver fluke is snail and the primary host is vertebrate (sheep, human etc). The first larval stage is miracidium which enters the intermediate host (snail). Primary host is infected by metacercaria. Cercaria covered by cyst is called metacercaria which is present on grasses and are engulfed by sheep (primary host).