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: Pharmacology
Morphine causes vomiting by acting on- 
Select and explain. 
A. C.T.Z, B. Gastric mucosa, C. Both of the above, D. None of the above
A: C.T.Z
Answer: A: C.T.Z 
Explanation: Ans. is 'a' i.e., C.T.Z