This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology, Subject name: Medicine
Increased Ca, decreased PO4. Diagnosis : - 
Select and explain. 
A. Primary hyperparathyroidism, B. Secondary hypoparathyroidism due to Vit D deficiency, C. Malignancy, D. Osteoporosis
A: Primary hyperparathyroidism
Answer: A: Primary hyperparathyroidism 
Explanation: Ans. is 'a' i.e., Primary hyperparathyroidism o Repeat from previous session.