What is the estimated amount of concentrate needed to kill an average person in category 4?

In the context of toxic substances, category 4 indicates a relatively lower level of acute toxicity compared to higher categories. The estimated amount of concentrate needed to cause significant harm or potentially be lethal varies greatly depending on the specific substance and individual susceptibility.

The choice indicating "greater than a pint" aligns with the understanding that while category 4 substances require larger quantities to be lethal due to their lower toxicity, it can still be dangerous in large doses. Typically, a pint or more signifies that it takes a considerable amount of the chemical to reach a harmful dose, as substances in this category are designed to have a greater safety margin. Thus, the suggestion that it takes more than a pint accurately reflects the toxicological profile for substances categorized this way, where the risk of fatality increases with the volume consumed.

In contrast, the other options imply smaller quantities that would not be consistent with the broader understanding of category 4 toxicity levels. Therefore, the chosen answer appropriately illustrates the amount required to pose a significant risk based on the defined toxicity levels.