**Core Concept:** Reflux nephropathy is a condition caused by the backflow of urine from the bladder into the ureters and kidney, leading to tubulointerstitial nephritis and scarring. Nephrotic range proteinuria occurs when the glomerular filtration barrier is compromised, leading to massive protein loss in the urine.

**Why the Correct Answer is Right:** The correct answer is D, which refers to "Interstitial Fibrosis and Tubular atrophy." In reflux nephropathy, the prolonged exposure to urine toxins causes inflammation and damage to the renal tubules and interstitium. This leads to fibrosis (scarring) and tubular atrophy, which are the histological hallmarks of this condition.

**Why Each Wrong Option is Incorrect:**

A. Glomerulonephritis (Option A) is characterized by inflammation of the glomerulus, not the interstitium and tubules.
B. Polycystic kidney disease (Option B) is characterized by the formation of multiple cysts in the kidneys, not fibrosis and tubular atrophy.
C. Lupus nephritis (Option C) is associated with inflammation and damage in the glomeruli, not fibrosis and tubular atrophy.

**Why Reflux Nephropathy is the Most Likely Histological Finding:** The correct answer (D) is the most likely histological finding in a patient with radiologically confirmed reflux nephropathy and nephrotic-range proteinuria, as the condition primarily affects the interstitium, tubules, and glomeruli, leading to proteinuria. The other options focus on different renal diseases that do not present with nephrotic range proteinuria or have different histological findings.

**Clinical Pearl:** Understanding the histological findings in various kidney diseases is crucial for accurate diagnosis and appropriate management. This knowledge enables clinicians to tailor treatment strategies to protect renal function and minimize long-term complications.