Which of the following statements regarding LD50 levels is true?

When evaluating toxicity levels indicated by LD50, it's essential to understand that LD50 refers to the median lethal dose, which is the dose required to kill half the members of a tested population after a specified test duration. The lower the LD50 value, the more toxic the substance is, as it means that a smaller amount is needed to achieve lethal effects.

The statement that an insecticide with an LD50 of 2 is 12.5 times less toxic than one with an LD50 of 25 accurately reflects the relationship between these two values. This conclusion derives from the understanding that a substance with a lower LD50 requires significantly less exposure to reach toxic levels compared to one with a higher LD50. So comparing the two, the substance with the LD50 of 2 is indeed much more lethal than the one with an LD50 of 25.

To clarify the ramifications of comparison: a substance with an LD50 of 2 will cause death at a much smaller dose than one with an LD50 of 25, thus categorizing the lower LD50 substance as significantly more toxic. This illustrates the principle that a smaller number in the context of LD50 correlates with greater toxicity. Therefore, stating that the insecticide with an LD50