Pepsinogen is produced by______________ and is activated by__________

A. Glomerulus is involved in filtering blood but not in producing hypertonic urine.

B. Collecting duct reabsorbs water and concentrates urine, making it hypertonic.

C. Nephron loop (loop of Henle) creates a concentration gradient in the medulla that helps in water reabsorption but is not the primary site for final urine concentration. This option is partially correct but less specific than the collecting duct.

D. Proximal convoluted tubule reabsorbs a significant portion of water and solutes but does not produce hypertonic urine.

A. Glomerular capillaries are involved in the filtration of blood to form the glomerular filtrate, not in the reabsorption of glucose and amino acids.

B. Proximal convoluted tubule is where the majority of glucose and amino acids are reabsorbed from the glomerular filtrate back into the bloodstream.

C. Renal corpuscle consists of the glomerulus and Bowman's capsule and is involved in the filtration process, not in reabsorption.

D. Distal convoluted tubule is involved in the fine-tuning of electrolyte and acid-base balance, not in the primary reabsorption of glucose and amino acids.