This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
Giardia trophozoites in endoscopic study and biopsy of the duodenum is seen in: 
Select and explain. 
A. Lactase deficiency, B. Whipples disease, C. Abetelipoprotenemia, D. Immune globulin deficiency
D: Immune globulin deficiency
Answer: D: Immune globulin deficiency 
Explanation: Biopsy of the small intestinal mucosa: Diffuse and specific lesions are seen in: 1. Whipple's disease Presence of periodic acid-Schiff (PAS)-positive macrophages in the lamina propria 2. Abetalipoproteinemia Normal mucosal appearance except for the presence of mucosal cells contain lipid postprandially and disappear following a prolonged period of fasting. 3. Immune globulin deficiency: Absence of plasma cells in the lamina propria; the mucosal architecture may be either perfectly normal or flat (i.e., villous atrophy). Patients are often infected with Giardia lamblia,Giardia trophozoites seen in the biopsy Ref: Harrison, E-18, P-2468.