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
A patient Geeta began taking alendronate and she was advised to take a large amount of water and remain in the standing position for at least half an hour till she had the first meal of the day. These instructions were given to reduce the risk of: 
Select and explain. 
A. Cholelithiasis, B. Constipation, C. Erosive esophagitis, D. Osteonecrosis
C: Erosive esophagitis
Answer: C: Erosive esophagitis 
Explanation: None