This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Gastro-Intestinal Tract, Subject name: Pharmacology
The success of oral rehydration therapy of diarrhea depends upon which of the following processes in the intestinal mucosa? 
Select and explain. 
A. Sodium pump mediated Na+ absorption, B. Glucose coupled Na+ absorption, C. Bicarbonate coupled Na+ absorption, D. Passive Na+ diffusion secondary to nutrient absorption
B: Glucose coupled Na+ absorption
Answer: B: Glucose coupled Na+ absorption 
Explanation: Glucose coupled Na+ absorption from GIT remain patent even in presence of severe diarrhea whereas other mechanisms may fail. Thus, glucose is added in the ORS.