What is the role of the kidneys in the body?

• A. To circulate blood and oxygen
• B. To filter blood and produce urine
• C. To aid in digestion
• D. To synthesize proteins

Answer: (B)

The kidneys play a crucial role in maintaining homeostasis within the body, primarily through their function of filtering blood and producing urine. This filtration process helps remove waste products, excess substances, and toxins from the bloodstream, which are then excreted in urine.

Additionally, the kidneys regulate important physiological functions such as electrolyte balance, blood pressure, and the acid-base balance of the body. By filtering the blood, they also help manage fluid balance, ensuring that the body retains the necessary amounts of water and electrolytes while disposing of what is not needed.

In contrast, the other options represent functions that are not associated with the kidneys. The circulation of blood and oxygen is primarily the function of the heart and the cardiovascular system, digestion is handled by the gastrointestinal tract, and protein synthesis occurs mainly in the liver and cells throughout the body. Thus, the primary and most significant function of the kidneys is accurately captured in the correct answer.