This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Disorders of pituitary gland, Subject name: Medicine
L- arginine test is used for testing reserve of? 
Select and explain. 
A. Prolactin, B. Cosyntropin test, C. Metyrapone test, D. Growth hormone
D: Growth hormone
Answer: D: Growth hormone 
Explanation: Tests used for testing reserves of hormones GH Insulin tolerance test GHRH test L-arginine test L-dopa test Prolactin TRH stimulation test Cosyntropin test ACTH effect on plasma coisol Metyrapone test ACTH effect on plasma coisol