**Core Concept**
Hydrogen cyanide (HCN) is a highly toxic compound that exerts its effects through the inhibition of cellular respiration. It binds to cytochrome c oxidase in the mitochondria, preventing the transfer of electrons and thereby disrupting the production of ATP.

**Why the Correct Answer is Right**
HCN's mechanism of action involves the formation of a stable complex with the iron atom in cytochrome c oxidase, effectively blocking the electron transport chain. This leads to a rapid decrease in cellular ATP production, resulting in cellular asphyxiation. The inhibition of cytochrome c oxidase is irreversible, making HCN a potent and deadly toxin.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as HCN does not primarily affect the sodium-potassium pump.
**Option B:** This option is incorrect as HCN does not primarily affect the calcium channels.
**Option C:** This option is incorrect as HCN does not primarily affect the acetylcholine receptors.

**Clinical Pearl / High-Yield Fact**
HCN's potent toxicity is due to its ability to inhibit cellular respiration, leading to rapid depletion of ATP stores. This makes HCN a highly lethal compound, with even small exposures posing a significant risk to human life.

**Correct Answer:** D. Inhibition of cellular respiration.