Final answer:
About 98-99% of the kidney filtrate is reabsorbed back into the vascular system, a process mainly controlled by the proximal convoluted tubule and hormones that regulate the final water reabsorption in the collecting ducts.
So, the correct answer is B.
Step-by-step explanation:
The amount of kidney filtrate that is reabsorbed back into the vascular system is 98-99%. The kidneys produce a significant volume of filtrate each day, about 180 liters in males and 150 liters in females, but only about 1-2 liters end up as urine. This is because the glomerular filtration rate (GFR) and tubular reabsorption mechanisms in the kidneys are incredibly efficient, recovering most of what is initially filtered out of the blood. The majority of this reabsorption takes place in the proximal convoluted tubule (PCT), where substances like glucose, amino acids, and other organic compounds are normally fully recovered. Water and electrolyte balance are tightly regulated by hormones such as antidiuretic hormone (ADH) and aldosterone, which adjust the amount of water reabsorbed in the collecting ducts.
In summary, the correct answer is B. 98-99%.