Which statement correctly defines herbicide selectivity?

• A. It is the ability of a herbicide to kill certain weed species without significant injury to crops.
• B. It means the herbicide is safe for all crops in all conditions.
• C. It means the herbicide has high toxicity to humans.
• D. It indicates the herbicide works only in shaded areas.

Answer: (A)

Herbicide selectivity means the herbicide can control or kill certain weed species while causing little or no injury to the crop it’s applied to. This happens because crops and weeds differ in how they take up, metabolize, and tolerate the chemical, and by choosing the right product, timing, and rate, growers can target weeds without harming the crop. That idea is captured by describing selectivity as killing weeds with minimal crop injury.

If you see other statements: saying a herbicide is safe for all crops in all conditions isn’t accurate, since no product is universally safe for every crop in every situation. Saying it has high toxicity to humans confuses the concept of crop selectivity with human health toxicity. Saying it works only in shaded areas misrepresents what determines performance, which is more about crop–weed sensitivity and timing than light conditions.