This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T, Subject name: Medicine
Antiemetic of choice in chemotherapy induced vomiting - 
Select and explain. 
A. Metaclopramide, B. Ondansetron, C. Prochlorperazine, D. Nabilone
B: Ondansetron
Answer: B: Ondansetron 
Explanation: Ondansetron, marketed under the brand name Zofran, is a medication used to prevent nausea and vomiting caused by cancer chemotherapy, radiation therapy, or surgery. It is also useful in gastroenteritis. It has little effect on vomiting caused by motion sickness. It can be given by mouth, or by injection into a muscle or into a vein. Ref Davidson edition23rd pg 805