What is the role of a rain sensor in irrigation control?

• A. To automatically stop irrigation when rainfall meets a predefined threshold, conserving water.
• B. To initiate irrigation when rainfall occurs.
• C. To monitor soil pH levels.
• D. To measure wind speed.

Answer: (A)

Rain sensors are used to automatically adjust irrigation based on rainfall, helping to conserve water. They detect rain and pause or override the irrigation controller when a predefined amount has fallen, so watering isn’t wasted after or during rain. This prevents overwatering and runoff and can resume watering once the soil dries to a set threshold. The other options don’t fit because a rain sensor’s job isn’t to start irrigation during rain, to monitor soil pH, or to measure wind speed.