**Core Concept**
Copper sulphate poisoning affects multiple organ systems, but the primary cause of death is related to the toxic effects of copper on the cardiovascular system and the central nervous system.

**Why the Correct Answer is Right**
Death in copper sulphate poisoning is primarily due to severe metabolic acidosis, leading to cardiovascular collapse and respiratory failure. Copper ions (Cu2+) inhibit the enzyme cytochrome c oxidase in the mitochondrial electron transport chain, disrupting cellular respiration and leading to an accumulation of lactic acid, which contributes to the metabolic acidosis.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to the primary cause of death in copper sulphate poisoning.
**Option B:** While liver damage is a potential consequence of copper sulphate poisoning, it is not the primary cause of death.
**Option C:** Cardiac arrest is a potential consequence of severe metabolic acidosis, but it is not the direct cause of death in copper sulphate poisoning.

**Clinical Pearl / High-Yield Fact**
Copper sulphate poisoning can be treated with penicillamine, a chelating agent that binds to copper ions, helping to reduce their toxic effects. However, treatment should be initiated promptly, as the effectiveness of chelation therapy decreases with time.

**Correct Answer: A. Metabolic acidosis.**