This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Parathyroid and adrenal glands, Subject name: Surgery
Most common cause for primary hyperparathyroidism is: 
Select and explain. 
A. Single adenoma, B. Multiple adenomas, C. Single gland hyperplasia, D. Multiple gland hyperplasia
A: Single adenoma
Answer: A: Single adenoma 
Explanation: - Solitary adenoma is the most common cause (80%) - Parathyroid adenomas are most commonly located in inferior parathyroid glands Primary Hyperparathyroidism (PHPT)- Caused by increased secretion of Parathyroid hormone (PTH) from abnormalparathyroid gland- More common in females- MC cause of PHPT - Solitary Adenoma (80% of cases)|MC location - Inferior parathyroid