Which statement about contact herbicides is true?

• A. They kill underground parts of the plant.
• B. They do not kill underground parts of the plant.
• C. They are systemic and move to roots.
• D. They provide long-term soil residual control.

Answer: (B)

Contact herbicides act on the tissue they touch, and they don’t move inside the plant to reach roots or other underground parts. Because they stay where the spray contacts the plant, they primarily injure or kill the exposed foliage or stems that were wetted, not the underground structures. They also tend to break down quickly in soil, so they don’t provide long-term soil residual control. The statements about systemic movement to roots or lasting soil residues don't fit how these products work, and that’s why this option is correct.