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
Which one of the following drugs is useful in the treatment of gastroesophageal reflux disease? 
Select and explain. 
A. Atropine, B. Ondansetron, C. Metoclopramide, D. Sodium citrate
C: Metoclopramide
Answer: C: Metoclopramide 
Explanation: Metoclopramide is an effective drug in the treatment of patients with GERD. It is a prokinetic drug that speeds up gastric emptying by increasing gastric peristasis while relaxing the pylorus and first pa of duodenum. It also enhance the tone of lower esophageal sphincter thereby preventing reflux. Ref: Essentials of Medical Pharmacology, 5th Edition, Pages 602, 605-606