The most important environmental factors influencing spray drift are.

• A. Other factors
• B. Wind speed and direction
• C. Wind direction and relative humidity
• D. Wind speed and UV intensity

Answer: (B)

Spray drift is driven mainly by air movement after the spray leaves the nozzle. The wind pushes droplets along and carries them downwind; the stronger the wind, the farther the droplets can travel before settling. The direction of that air flow also matters because it determines exactly where the droplets go relative to the target. Among the factors listed, wind speed and wind direction have the strongest and most direct influence on how far and in what direction the spray moves, making them the best answer. Humidity can affect evaporation and droplet size, but it doesn’t control drift as directly as wind does; UV intensity doesn’t significantly affect spray droplet movement.