Which herbicide is broadleaf selective and can leach into groundwater readily in poor sandy soils, though it is broken down by microbial degradation, with a persistence of 20-100 days?

• A. 2,4-D
• B. Bromacil
• C. Glyphosate
• D. Hexazinone

Answer: (A)

The main idea here is how a broadleaf-selective herbicide can pose groundwater leaching risk in certain soils while still being broken down by soil microbes, giving a moderate window of persistence. 2,4-D is a classic broadleaf herbicide that targets dicot weeds but largely spares grasses. In poor, sandy soils it tends to be less strongly sorbed to soil particles, so water moving through the profile can transport some of it downward and toward groundwater. At the same time, soil microbes readily degrade 2,4-D, which prevents long-term buildup and keeps its persistence in a moderate range—roughly weeks to a few months, often cited around 20–100 days depending on conditions. This combination of broadleaf selectivity, potential for groundwater movement in sandy soils, and microbial degradation aligns with the described profile for 2,4-D. Other options have different behavior: some are more persistent or more leachable, some are non-selective, or they don’t fit the specific broadleaf-selective and groundwater-leaching pattern described here.