**Core Concept**
The Glomerular Filtration Rate (GFR) is the volume of fluid filtered from the renal plasma into the Bowman's capsule per unit time. It is an essential parameter for assessing kidney function.

**Why the Correct Answer is Right**
To calculate the filtration fraction, we need to divide the GFR by the renal plasma flow (RPF). The formula for filtration fraction is: Filtration Fraction = GFR / RPF. Given GFR = 125 ml/min and RPF = 625 ml/min, we can plug in the values to get the filtration fraction.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not provided.
**Option B:** This option is not provided.
**Option C:** This option is not provided.
**Option D:** This option is not provided.

**Clinical Pearl / High-Yield Fact**
The filtration fraction is a critical parameter in assessing kidney function, as it helps in diagnosing and managing conditions such as glomerulonephritis and nephrotic syndrome. A normal filtration fraction ranges from 0.15 to 0.20.

**Correct Answer: D. 0.20.**