What characteristic defines non-selective herbicides?

Non-selective herbicides are defined by their ability to harm most or all plants they come into contact with. This characteristic makes them effectively destructive to a wide range of unwanted vegetation, which is particularly useful in scenarios where the goal is to clear a site of all plant life, such as during land preparation or maintenance of paths and driveways.

The mode of action for non-selective herbicides typically involves disrupting critical physiological processes in plants, which can lead to the death of the targeted plants. This broad-spectrum efficacy is at the core of what makes non-selective herbicides valuable in agricultural and landscaping applications, as they can provide quick results in terms of weed control when applied appropriately.

The other options describe characteristics that are either not inherent to non-selective herbicides or misinterpret their function. For instance, non-selective herbicides can indeed be harmful to animals if they contact treated areas or ingest the plants that have absorbed the chemicals, and they do not specifically target just broad-leaved plants, nor do they maintain soil structure, as their use can alter the conditions within the soil ecosystem.