**Core Concept**
The venom of sea snakes contains a complex mixture of enzymes and proteins that have distinct pharmacological effects on the human body. Specifically, the venom of sea snakes is primarily composed of phospholipase A2 (PLA2) enzymes, which play a crucial role in its myotoxic activity.

**Why the Correct Answer is Right**
The myotoxic effect of sea snake venom is mediated by the PLA2 enzymes, which target the muscle cells and cause damage to the sarcoplasmic reticulum. This leads to the release of calcium ions, which in turn activates the myofibrils and causes muscle necrosis. The myotoxic activity of sea snake venom is responsible for the severe muscle pain, weakness, and respiratory failure observed in envenomed individuals. The PLA2 enzymes are highly specific to the muscle tissue, which is why the venom is considered myotoxic rather than neurotoxic, haemolytic, or hepatotoxic.

**Why Each Wrong Option is Incorrect**
**Option A:** Neurotoxic venom typically affects the nervous system, causing symptoms such as respiratory failure, paralysis, and cardiac arrest. Sea snake venom does not primarily target the nervous system, making this option incorrect.
**Option B:** Haemolytic venom causes the breakdown of red blood cells, leading to haemolysis and haemoglobinuria. Sea snake venom does not have significant haemolytic activity, making this option incorrect.
**Option D:** Hepatotoxic venom causes damage to the liver, leading to liver dysfunction and failure. Sea snake venom does not primarily target the liver, making this option incorrect.

**Clinical Pearl / High-Yield Fact**
The PLA2 enzymes in sea snake venom are highly specific to the muscle tissue and are responsible for the myotoxic effects. This is why the venom is often used as a model for studying muscle damage and necrosis in humans.

**Correct Answer:**
✓ Correct Answer: C. Myotoxic