This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Medical, surgical and gynaecological illness complicating pregnancy, Subject name: Gynaecology & Obstetrics
Which of the following drug is category B (adequate studies in pregnant woman have failed to demonstrate a fetal risk)? 
Select and explain. 
A. Ranitidine, B. Pilocarpine, C. Latanoprost, D. Dorzolamide
A: Ranitidine
Answer: A: Ranitidine 
Explanation: Category B drugus are the one that have shown no risks in animal studies, but human studies do not exist or also if adverse effect have been seen in animal studies with no such effect im well controlled human trials. eg.ranitidine,paracetamol. TEXT BOOK OF OBSTETRICS,Sheila Balakrishnan,2nd edition,page no.564