Which list correctly names the three types of herbicides?

• A. Pre-emergence, Post-emergence, Systemic
• B. Pre-emergence, Contact, Systemic
• C. Pre-emergence, Contact, Foliar
• D. Pre-emergence, Contact, Soil-acting

Answer: (B)

Herbicides are most usefully understood by how they move in the plant and when they’re applied. The three types here are pre-emergence, contact, and systemic.

Pre-emergence herbicides are applied to the soil before weeds germinate, so they prevent weeds from getting established as seeds sprout. Contact herbicides kill only the plant tissue they touch; they don’t travel inside the plant, so the death is limited to areas that the spray directly contacts. Systemic herbicides are absorbed into the plant and translocated to other tissues, allowing the whole plant to die even if only some parts were sprayed.

This combination—one timing category (pre-emergence) plus two action types (contact and systemic)—is why that list is the best fit. Other lists mix in post-emergence or soil-acting terms, which describe different concepts not grouped with these three in this context.