**Core Concept**
Filtration pressure in glomeruli is a critical factor in the glomerular filtration rate (GFR), which determines the rate at which the kidneys filter waste and excess fluids from the blood. The glomerular filtration barrier consists of the fenestrated endothelium, the glomerular basement membrane, and the podocytes, which all contribute to the filtration process.

**Why the Correct Answer is Right**
The filtration pressure in the glomeruli is primarily generated by the difference in hydrostatic pressure between the blood within the glomerular capillaries and the capillaries of the efferent arteriole. The hydrostatic pressure within the glomerular capillaries is approximately 55 mmHg, while the oncotic pressure is around 30 mmHg. The hydrostatic pressure in the efferent arteriole is lower, approximately 10-15 mmHg. This pressure gradient drives the movement of fluid from the blood into the Bowman's space, where it is collected as filtrate. The correct answer is based on the Starling forces, which describe the balance between the hydrostatic and oncotic pressures across the glomerular filtration barrier.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the correct filtration pressure value is not provided. While it's true that the filtration pressure is influenced by the hydrostatic pressure, the actual value is not specified here.

**Option B:** This option is incorrect because the value of 20 mmHg is not the correct filtration pressure in glomeruli. Although the hydrostatic pressure within the glomerular capillaries is around 55 mmHg, the actual filtration pressure is influenced by multiple factors, including the oncotic pressure and resistance within the glomerular capillaries.

**Option C:** This option is incorrect because the value of 10 mmHg is close to the hydrostatic pressure in the efferent arteriole but does not accurately represent the filtration pressure in the glomeruli.

**Clinical Pearl / High-Yield Fact**
The glomerular filtration rate (GFR) is a critical determinant of kidney function, and a decrease in GFR is associated with various renal diseases, including chronic kidney disease and acute kidney injury. The GFR can be estimated using the Modification of Diet in Renal Disease (MDRD) equation, which takes into account the serum creatinine levels and age of the patient.

**Correct Answer:** C. 20 mmHg