This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: parasitic infection, Subject name: Medicine
Patient presents with complaints of lower abdominal pain, fever and repeated stools with little faecal matter and blood and mucus. On microscopy paucity of WBCs in stool with positive test for heme. Which is the likely organism? 
Select and explain. 
A. Giardia, B. Entamoeba, C. Staphylococcus, D. Clostridium perfringens
B: Entamoeba
Answer: B: Entamoeba 
Explanation: Amoebic dysentery: Entamoeba histolytica Rx- Metronidazole Giardia: No heme so,ruled out Staphylococcus: - Toxin: causes vomiting, so ruled out Clostridium perfringes: Watery diarrhoea, so ruled out