Final answer:
The process in urine formation where nutrients, ions, and water are returned to the body is called Tubular reabsorption. It primarily occurs in the PCT and continues along parts of the nephron.
Step-by-step explanation:
The process of urine formation involves several steps. The correct answer to the question 'In which process of urine formation are nutrients, ions, and water returned to the body?' is B. Tubular reabsorption. During tubular reabsorption, useful substances like nutrients, ions, and water are reclaimed after they have been filtered out in the glomerulus. This process occurs primarily in the proximal convoluted tubule (PCT), but also continues in the loop of Henle and the distal convoluted tubule (DCT), with the reabsorbed substances returning to the bloodstream. By contrast, glomerular filtration is a process where blood plasma is filtered into the glomerulus, tubular secretion deals with the addition of certain wastes from the blood into the tubular fluid, and elimination and micturition are the processes of expelling urine from the body.