Explanation:

- Correct Answer: Option 3: Silver Iodide

- Silver iodide is commonly used for cloud seeding, a process aimed at enhancing precipitation.

- It works by providing nuclei around which moisture droplets can form in the clouds, eventually leading to rain.

- Option 1: Copper Sulphate

- Copper sulfate is not used for cloud seeding; it's primarily used as a fungicide and herbicide in agriculture.

- Option 2: Ammonium Nitrate

- Ammonium nitrate is a common agricultural fertilizer and also used as an explosive, but not for cloud seeding.

- Option 4: Potassium Permanganate

- Potassium permanganate is mainly used as a disinfectant and in water treatment processes, not in cloud seeding.

In summary, Silver Iodide is the correct choice for artificial rain production through cloud seeding.