The kidneys produce renin when
A. the urine becomes acidic.
B. the peritubular capillaries dilate.
C. the blood pressure in the afferent arteriole decreases.
D. sodium chloride concentration in the distal convoluted tubule increases.
E. the blood pressure in the afferent arteriole increases.
Answer: C. the blood pressure in the afferent arteriole decreases.