**Core Concept**
The Glomerular Filtration Rate (GFR) is a critical measure of renal function, representing the volume of fluid filtered from the renal glomerular capillaries into the Bowman's capsule per unit time. GFR is influenced by various factors, including renal blood flow, glomerular hydrostatic pressure, and the permeability of the glomerular capillary walls.

**Why the Correct Answer is Right**
An increase in GFR typically occurs when there is an increase in renal blood flow or glomerular hydrostatic pressure. This can be caused by factors such as increased cardiac output, vasodilation of the renal arteries, or decreased resistance in the glomerular capillaries. The correct answer is associated with an increase in renal blood flow, which directly contributes to an increase in GFR.

**Why Each Wrong Option is Incorrect**
**Option A:**
This option is incorrect because a decrease in renal blood flow would lead to a decrease in GFR, not an increase.

**Option B:**
This option is incorrect because a decrease in glomerular hydrostatic pressure would also lead to a decrease in GFR.

**Option C:**
This option is incorrect because an increase in resistance in the glomerular capillaries would lead to a decrease in GFR, not an increase.

**Clinical Pearl / High-Yield Fact**
In patients with heart failure or severe hypertension, an increase in renal blood flow can be a compensatory mechanism to maintain GFR, but it may also lead to fluid overload and worsening of symptoms. Monitoring renal function and fluid status is crucial in these patients.

**Correct Answer: D. Increased renal blood flow.**