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: Physiology
Glucose transpo occur with the help of following ion in absorption in gut region 
Select and explain. 
A. Na+, B. K+, C. Ca+, D. CI-
A: Na+
Answer: A: Na+ 
Explanation: Glucose is absorbed into the epithelial cells lining the mucous membrane of the small intestine from their brush border surface by an active transpo mechanism Sodium co-transpo mechanism. Binding of glucose & Na+ to carrier protein: The carrier protein in cell membrane has 2 binding sites, one for sodium & another for glucose.It is called sodium-dependent glucose transpoer-I. The conformational change in the carrier protein occurs only when the binding sites are occupied by the sodium & glucose present in the gut lumen forming the sodium- glucose - carrier complex. Ref: Medical Physiology, Indu Khurana