Okay, let's tackle this question. The patient is an 8-year-old with a history of severe sore throat two weeks ago, now presenting with headaches, dizziness, malaise, facial edema, high blood pressure (180/110), oliguria, and hematuria. The question is asking for the correct diagnosis.

First, I need to recall the possible conditions that fit these symptoms. The key points here are the recent sore throat and the subsequent symptoms. High blood pressure, facial edema, oliguria, and hematuria are classic signs of acute glomerulonephritis. Post-streptococcal glomerulonephritis (PSGN) is a common cause in children after a streptococcal infection. The time frame is about two weeks after the sore throat, which is consistent with PSGN's typical latency period.

Now, looking at the options (though they're not listed here, but the correct answer is likely one of the common differentials). Let's consider other possibilities. Nephrotic syndrome usually presents with heavy proteinuria, hypoalbuminemia, and edema, but less so with hematuria and hypertension. Acute pyelonephritis would have fever, flank pain, and maybe dysuria. Malignant hypertension is a severe form but less likely in a child without a history suggesting it. Henoch-Schönlein purpura (HSP) can cause glomerulonephritis but usually with a rash, joint pain, and abdominal pain.

The core concept here is the pathophysiology of PSGN. It's an immune complex-mediated glomerulonephritis following a streptococcal infection. The immune complexes deposit in the glomeruli, leading to inflammation, hematuria, proteinuria, and hypertension. The edema is due to sodium and water retention from reduced glomerular filtration. Facial edema is typical because of gravity; the face is the first area to show fluid accumulation.

For the wrong options, if one of them was nephrotic syndrome, the absence of massive proteinuria and the presence of hematuria would make it incorrect. If another option was HSP, the lack of the characteristic rash and other systemic symptoms would rule it out. Acute pyelonephritis is less likely due to the absence of systemic infection signs. Malignant hypertension is a more acute presentation with severe hypertension and retinal changes, which isn't mentioned here.

The clinical pearl is to remember the classic triad of PSGN: hematuria, hypertension, and edema, following a streptococcal infection. Also, the time frame of 1-2 weeks after the infection. The mnemonic "PSGN after strep throat" can help. Another point is that PSGN is more common in children and adolescents, which fits this patient's age.

**Core Concept**
This question assesses the pathophysiology and clinical presentation of **post-streptococcal glomerulonephritis (PSGN)**, an immune complex-mediated glomerulonephritis following a streptococcal infection. Key features include hematuria, hypertension, edema, and oliguria occurring 1–2 weeks post-infection.

**Why the Correct Answer is Right**
The patient’s history of a **severe sore throat 2 weeks prior

✓ Correct Answer: D. Postinfectious glomerulonephritis