Glomerular capillaries are specialized capillaries located in the kidneys that play a crucial role in filtering blood and producing urine. Blood enters and leaves these capillaries through specific arterioles, which are small blood vessels that regulate blood flow in and out of the capillaries. The correct answer to the question is d) Afferent, Efferent.

Afferent Arteriole:
- The afferent arteriole is the small blood vessel that brings blood into the glomerular capillaries.
- It is wider than the efferent arteriole, allowing for greater blood flow into the capillaries.
- The afferent arteriole is responsible for maintaining the high pressure necessary for efficient filtration of blood in the glomerulus.

Efferent Arteriole:
- The efferent arteriole is the small blood vessel that carries blood out of the glomerular capillaries.
- It is narrower than the afferent arteriole, which creates a high resistance to blood flow and helps to maintain the high pressure in the capillaries.
- The efferent arteriole is responsible for regulating blood flow and pressure in the capillaries, which affects the rate of filtration and urine production.

Importance of Blood Flow in Glomerular Capillaries:
- The afferent and efferent arterioles play an essential role in maintaining blood flow and pressure in the glomerular capillaries.
- Proper blood flow is necessary for efficient filtration of blood and production of urine.
- Changes in blood flow and pressure can lead to kidney damage and dysfunction.

In conclusion, blood enters the glomerular capillaries through the afferent arteriole and leaves through the efferent arteriole. Understanding the roles of these arterioles is essential for maintaining kidney function and preventing kidney disease.