## Core Concept
Ammonia is a toxic substance that affects the body, particularly the nervous system. It is a product of nitrogen metabolism and can cause damage through various mechanisms. The primary concern with ammonia toxicity is its effect on the brain.

## Why the Correct Answer is Right
The correct answer, **C. Cerebral edema**, is related to the fact that ammonia disrupts the blood-brain barrier and causes astrocytes to swell, leading to cerebral edema. Ammonia is detoxified in the brain by conversion to glutamine via the enzyme glutamine synthetase, using glutamate. This process can lead to astrocyte swelling and cerebral edema.

## Why Each Wrong Option is Incorrect
* **Option A:** This option is incorrect because, although ammonia does affect the body, the primary and most direct effect related to the options provided is not explicitly listed here, but cerebral edema is a well-documented consequence.
* **Option B:** This option is incorrect as it does not accurately represent a primary effect of ammonia toxicity in the context provided.
* **Option D:** This option is incorrect because it does not accurately describe a primary consequence of ammonia toxicity.

## Clinical Pearl / High-Yield Fact
A key point to remember is that ammonia toxicity can lead to **hepatic encephalopathy**, a condition that results from liver disease. The brain's detoxification of ammonia is critical, and failure of the liver to clear ammonia leads to its accumulation and neurological symptoms.

## Correct Answer: C. Cerebral edema