**Core Concept**
Paraphenylenediamine (PPD), a common ingredient in hair dyes, is a potent haptene that can trigger severe allergic reactions. When ingested, it undergoes metabolic activation and causes systemic toxicity, particularly affecting the kidneys and muscles due to oxidative stress and mitochondrial dysfunction.

**Why the Correct Answer is Right**
Ingestion of PPD leads to acute toxicity, primarily involving the kidneys and skeletal muscle. The compound induces oxidative stress, leading to muscle cell damage and release of intracellular contents such as creatine kinase. This results in rhabdomyolysis — a condition characterized by muscle breakdown, hyperkalemia, and acute renal failure. Although dermatitis (option C) is a common reaction upon skin exposure, ingestion leads to systemic effects, with rhabdomyolysis being a well-documented, life-threatening consequence in severe cases.

**Why Each Wrong Option is Incorrect**
Option A: Blindness is not a known direct effect of PPD ingestion. While ocular toxicity can occur with topical exposure, it is not a hallmark of systemic toxicity.
Option B: Nerve pathology is not a primary feature of PPD toxicity. Neurological symptoms may occur in rare cases, but they are not characteristic or expected.
Option C: Dermatitis is a common **topical** reaction, not a systemic outcome after ingestion. The question specifies **ingestion**, so cutaneous effects are not the main concern.
Option D: Rhabdomyolysis is the most accurate expected outcome due to systemic metabolic toxicity and muscle damage.

**Clinical Pearl / High-Yield Fact**
Ingestion of hair dye components like PPD can lead to **acute rhabdomyolysis**, especially in young adults. Immediate management includes supportive care, hydration, and monitoring for acute kidney injury. Always consider systemic toxicity in cases of ingested hair dyes.

✓ Correct Answer: D. Rhabdomyolysis