Which of the following is an example of a highly toxic chemical?

The correct choice reflects a misunderstanding of the toxicity levels of the chemicals listed. Ethanol is widely known as a common alcohol found in beverages and has a relatively low toxicity profile in typical usage scenarios. N-Hexane, although it poses health risks, primarily affects the nervous system and is not classified as highly toxic in the way some other substances are. Acetic acid, while it can be corrosive at high concentrations, also does not fall into the category of highly toxic chemicals under standard conditions.

In this context, it's important to clarify that highly toxic chemicals are those that can cause severe harm or even death at low exposure levels. The options provided do not include examples that meet that stringent criterion. Instead, understanding the classifications of toxicity is key, such as differentiating between irritants, corrosives, and substances that are acutely toxic.