What is the principal characteristic of non-selective contact herbicides?

The principal characteristic of non-selective contact herbicides is that they are toxic to all plants. These herbicides work by coming into contact with plant tissues, leading to damage or death of the plants. Unlike selective herbicides, which are designed to target specific types of plants, non-selective herbicides do not discriminate—anything they touch can be harmed. This broad-spectrum action is particularly useful in situations where clear land is needed, such as preparing soil for new crops or controlling unwanted vegetation.

The other choices don't accurately describe non-selective contact herbicides. For example, the notion that they target only a specific type of weed is inaccurate as non-selective herbicides affect all species equally. Similarly, stating they affect only root systems overlooks their systemic capability to damage above-ground plant parts, and implying they only stunt plant growth temporarily misrepresents their potential, as they can lead to total plant destruction based on the concentration and exposure conditions.