This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Body composition and Acid base Balance, Subject name: Pediatrics
Calculate the plasma osmolality if serum Na+ is 130, glucose is 180 mg/dl, & BUN is 56, K+ is 5, cl- is 117. 
Select and explain. 
A. 260, B. 270, C. 280, D. 290
D: 290
Answer: D: 290 
Explanation: * Normal plasma osmolality = 285 - 295 mosm/kg *