This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Histamine, 5-HT and PGs, Subject name: Pharmacology
Which of the following drugs can cause hypotension by release of histamine from mast cells? 
Select and explain. 
A. Aspirin, B. Procaine, C. Morphine, D. Sulfadiazine
C: Morphine
Answer: C: Morphine 
Explanation: Basic drugs like morphine, d-TC(tubocurarine) and amphotericin B etc. act as histamine liberators and can cause acute reaction leading to itching and hypotension.