Final answer:
The correct pathway of glomerular filtrate is from the glomerulus, Bowman's capsule, PCT, loop of Henle, DCT, to the collecting duct, which is option (a) in the provided list.
Step-by-step explanation:
The correct order of the pathway for glomerular filtrate in the kidney nephron is the following sequence: glomerulus, Bowman's capsule, proximal convoluted tubule (PCT), loop of Henle, distal convoluted tubule (DCT), and finally the collecting duct. This process begins with the filtration of blood in the glomerulus, where almost all solutes except for proteins are filtered out by glomerular filtration.
The filtrate then enters the Bowman's capsule and moves to the PCT where most solutes are reabsorbed. Following this, the filtrate passes through the loop of Henle, descending and ascending, where additional water and solutes are reabsorbed, or sometimes secreted, altering the concentration of the filtrate. The filtrate next travels to the DCT where further reabsorption and secretion can occur, adjusting the content of solutes.
At last, the filtrate enters the collecting ducts, which gather filtrate from multiple nephrons. These ducts transport urine through the renal papillae into the calyces, and eventually to the ureters en route to the bladder. Therefore, the correct order of the pathway for the glomerular filtrate is indicated by option (a): 4, 5, 1, 3, 6, 2.