This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteriology, Subject name: Medicine
"In pseudomembranous colitis" the investigation of choice is ? 
Select and explain. 
A. Stool culture, B. CT scan abdomen, C. Glutamate dehydrogenase immunoassay, D. Sigmoidoscopy
B: CT scan abdomen
Answer: B: CT scan abdomen 
Explanation: Ans. is 'b' i.e., CT scan abdomen