This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Renal physiology, Subject name: Physiology
Glomerular feedback for decreased GFR is by 
Select and explain. 
A. Increased vasopressin activity, B. Increased PCT permeability, C. Increase renin JG complex, D. Increase renal sympathetic activity
C: Increase renin JG complex
Answer: C: Increase renin JG complex 
Explanation: Whenever blood flow to the kidney diminishes, renin is secreted and angiotensin is formed. The angiotensin causes widespread vasoconstriction and elevation of blood pressure consequent to greatly increased total peripheral resistance. A second effect, the increased secretion of aldosterone, results in retention of salt and water by the kidneys and therefore increased extracellular fluid volume, cardiac output, and aerial pressure. Additionally, the angiotensin acts directly on the kidneys to cause salt and water retention, which causes a long-term increase in aerial blood pressure.Ref: Ganong&;s Review of Medical Physiology, 23rd edition, page no: 669