The correct option is C Collecting tube
In human kidneys filtration occurs as blood pressure forces fluid from the blood in the glomerulus into the lumen of Bowman's capsule. The bowmans capsule are blind end of the nephron tubule forming a cup-shaped swelling, which surrounds the glomerulus. The porous capillaries and specialized cells of the capsule are permeable to water and small solutes, but not to blood cells or large molecules such as plasma proteins. Thus, the filtrate in Bowman's capsule contains salts, glucose, amino acids, vitamins, nitrogenous wastes, and other small molecules. Because filtration of small molecules is non selective, the mixture mirrors the concentrations of these substances in blood plasma. We cannot call the filtrate in Bowman's capsule as urine. It is called glomerular filtrate. The nephron and the collecting duct are lined by a transport epithelium that processes the filtrate, forming the urine. The fluid out of the collecting duct is called urine. Urine, consists of approximately 96% water, 2.5% nitrogenous wastes (mainly urea), 1.5% salts, and traces of other substances, such as bile pigments, that may contribute to the characteristic color and odor. As urine is produced, it flows from collecting ducts through a renal papilla and into the renal pelvis, a funnel-shaped chamber. Urine then flows into one of the paired ureters, ducts that connect each kidney with the urinary bladder. Healthy urine is sterile and has been used to wash battle field wounds when clean water was not available. However, when exposed to bacterial action, urine swiftly decomposes and forms ammonia and other products. Ammonia produces the diaper rash of infants.