Final answer:
Glomerular filtration occurs in the renal corpuscles; it is the process by which blood is filtered in the kidneys to begin the formation of urine.
Step-by-step explanation:
The process that occurs in the renal corpuscles is A. Glomerular filtration. The renal corpuscle consists of Bowman's capsule and the glomerulus, a network of capillaries. Here, the blood is filtered to create a filtrate that is mostly free of cells and large proteins. This filtrate is then captured and directed to the proximal convoluted tubule (PCT) for further modification. The other processes listed, such as tubular reabsorption, tubular secretion, elimination, and micturition occur at different stages in the nephron or are part of the urinary excretion pathway but are not functions of the renal corpuscle.