• Reservoir Host: The domestic pig (Sus scrofa) is the preeminent natural reservoir host for Fasciolopsis buski (the giant intestinal fluke of humans and swine).
• Epidemiology: Infected pigs shed massive quantities of unembryonated eggs into aquatic habitats. Freshwater planorbid snails (Segmentina, Hippeutis) serve as intermediate hosts, shedding cercariae that encyst as metacercariae on aquatic food plants (Trapa natans / water chestnut, Eleocharis tuberosa / water caltrop, Ipomoea aquatica / water spinach).
• Human Infection: Humans acquire infection when peeling water caltrops or water chestnuts with their teeth, ingesting metacercarial cysts.

Correct option: (2) Pig