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: Biochemistry
A 5 year old female patient complains of deformed shape of legs. Patient is a strict vegetarian. Lab investigations reveal elevated levels of alkaline phosphatase. This patient is suffering from deficiency of a vitamin whose recommended dietary allowance is- 
Select and explain. 
A. 300IU, B. 400IU, C. 500IU, D. 600IU
B: 400IU
Answer: B: 400IU 
Explanation: Deficiency of vitamin D causes rickets in children and osteomalacia in adults. The weight bearing bones are bent to form bow-legs.  In rickets, the plasma level of calcitriol  is  decreased  and  alkaline phosphatase  activity  is  elevated. The daily requirement of vitamin D is 400IU or 10 mg of cholecalciferol.
Satyanarayana- Biochemistry, 3rd edition, pg-127