question: A patient is having gastrointestinal problems including abdominal pain and distension, bloody or mucus-filled diarrhea, and tenesmus,with rectal prolapse, A stool, ova and parasites exam reveals the presence of typical Barrel-shaped eggs, possible causative agent is?
opa: Campylobacter
opb: Clostridium difficile
opc: Giardia lamblia
opd: Trichuris