What defines a selective herbicide?

A selective herbicide is defined by its ability to target specific types of plants while leaving others largely unharmed. This characteristic is crucial for managing unwanted plant species or weeds without disrupting the surrounding flora that may be desirable, such as crops, flowers, or turf.

Selective herbicides typically work by exploiting differences in plant physiology or biochemistry. For instance, they might affect specific growth pathways or metabolic processes that are more prevalent in certain plant types, thus minimizing damage to non-target plants. This is particularly important in agricultural settings, where maintaining the health of beneficial plants while controlling pests is essential for successful crop yields and ecosystem balance.

In contrast, a herbicide that kills all plants equally would be termed a non-selective herbicide and is used in situations where you want to clear a large area of all vegetation. A product absorbed only by the leaves does not inherently define selectivity; instead, it describes the mode of action. Additionally, a herbicide that is non-toxic to all animals does not relate to its selectivity regarding plant types but rather refers to its safety profile for animals. Therefore, the defining feature of a selective herbicide is its capability to harm certain plants while sparing others, making option B the correct choice.