This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Disorders of Parathyroid Gland, Subject name: Medicine
Low serum alkaline phosphatase is seen with 
Select and explain. 
A. Hypoparathyroidism, B. Hypophosphatasia, C. Hyperparathyroidism, D. Pseudo-hypoparathyroidism
B: Hypophosphatasia
Answer: B: Hypophosphatasia 
Explanation: SAP| - Hypophosphatasia SAP| - Rickets, increase PTH SAP|||- Paget's SAP Normal - Hypoparathyroidism,Pseudo hypoparathyroidism,Multiple myeloma,Osteoporosis