What is the main function of the efferent arteriole?

The main function of the efferent arteriole is to carry filtered blood away from the glomerulus. The glomerulus is a network of capillaries where blood filtration occurs in the kidneys. Once the blood has been filtered, it drains into the efferent arteriole, which transports the filtered blood out of the glomerulus and eventually leads to the peritubular capillaries surrounding the renal tubules. This process is crucial because it allows for the reabsorption and secretion of substances as the filtrate is transformed into urine.

The other options don't accurately describe the role of the efferent arteriole. While the role of bringing blood into the glomerulus is performed by the afferent arteriole, regulating blood pressure in the kidneys largely involves the actions of the afferent and efferent arterioles in a different context, and hormonal regulation involves other structures and processes not directly related to the flow of blood through the efferent arteriole.