As urine moves through a nephron, it is modified by ions, water, and other materials either being secreted into the fluid or by efflux of substances out of the urine. However, such modifications do not occur in which one of the following regions of the nephron?
a. proximal tubule
b. loop of henle
c. bowmans capsule
d. distal tubule
e. collecting duct

The bowman's capsule is a cup-shaped dilation which surrounds the glomerulus( tuft of capillaries). Bowman's capsule makes the first part of the nephron. Water and other solutes pass from the blood moving through the glomerulus into the Bowmans capsule due to glomerular blood pressure.

Then this filtrate passes through other part of nephron like PCT, Henle loop, DCT and collecting duct where secretion and absorption of substance and water takes place to make urine.

So Bowman's capsule just collects filtrate from the glomerulus and passes it to PCT, therefore, such modification does not occur in Bowman's capsule.