Final answer:
Blood exits the kidney through the efferent arteriole, which is narrower, resulting in higher pressure.
Step-by-step explanation:
The structure through which blood exits the kidney is the efferent arteriole, which is much narrower in diameter compared to the afferent arteriole that brings blood to the nephron. This smaller diameter results in higher pressure within the efferent arteriole. Consequently, the correct answer is c) Efferent arteriole, higher. In the nephron, blood first enters through the afferent arteriole and flows into the glomerulus, a high-pressure group of capillaries. As blood is filtered through the glomerulus, it exits via the efferent arteriole, which leads to a second capillary network, the peritubular capillaries and vasa recta, before returning to the venous circulation. The higher pressure in the efferent arteriole is essential for the kidney's function of filtering the blood and maintaining overall fluid balance.