The correct option is C Snail
Fasciola hepatica requires a freshwater snail as an intermediate host, such as Galba truncatula, in which the parasite can reproduce asexually. The discharged egg either opens in fresh water or in the intestine of the host. The egg turns to miracidium which is a free-living motile form, it is covered with cilia and settles in the mollusc to become a sporocyst.
So, the correct answer is option C.