Okay, let's tackle this question about the mortality rate in measles encephalitis. First, I need to recall the core concepts. Measles is a viral infection that can lead to various complications, one of which is encephalitis. The key here is to remember the statistics related to the severity of this complication.

The core concept would be the epidemiological data on measles complications. Measles encephalitis is a rare but serious complication. I think the mortality rate is quite high here. From what I remember, the mortality rate for measles encephalitis is around 10-15%, maybe even higher. But I need to be precise.

Now, the correct answer is probably one of the options that states a high percentage. Let's say the options were something like 10%, 30%, 50%, etc. The correct answer would be the one that's in the 10-15% range. Let me verify. According to the CDC and WHO, the mortality rate for measles encephalitis is approximately 10-20%. So if an option says 10%, that's correct.

For the wrong options: if there's an option like 1%, that's too low because encephalitis from measles is severe. If another option is 50%, that's too high; that might be the mortality rate for other complications like subacute sclerosing panencephalitis. Another wrong option could be 70%, which is even higher and not accurate for encephalitis.

Clinical pearl: Measles encephalitis is rare but has a high mortality rate, so vaccination is crucial. The key point is the mortality rate being around 10-15%, which is a high-yield fact for exams.

**Core Concept**
Measles encephalitis is a rare but severe complication of measles virus infection, characterized by inflammation of the brain. Its mortality rate is significantly higher than the overall measles case-fatality rate due to the severity of neurological involvement.

**Why the Correct Answer is Right**
The mortality rate in measles encephalitis is approximately **10-15%**. This occurs due to direct viral invasion of the central nervous system, leading to cerebral edema, neuronal damage, and potential herniation. Prompt supportive care is critical, but no specific antiviral therapy exists, contributing to the high fatality rate.

**Why Each Wrong Option is Incorrect**
**Option A:** *1%* – Incorrect. This underestimates the severity; encephalitis is a life-threatening complication.
**Option B:** *50%* – Incorrect. This overestimates mortality; 50% is closer to subacute sclerosing panencephalitis (SSPE), a late complication of measles.
**Option D:** *70%* – Incorrect. This is even higher than SSPE and not supported by clinical data for acute encephalitis.

**Clinical Pearl / High-Yield Fact**
Measles encephalitis mortality is **10–15%**, making it a critical differential in post-viral encephalitis. Vaccination prevents 90% of measles cases and nearly all severe complications.

**Correct Answer: C. 10-15%**

✓ Correct Answer: B. 10-20%