Step 1: Understanding the Concept:
Irrigation systems are classified into surface, sub-surface, drip (micro-irrigation), and sprinkler methods.
Sprinkler systems apply water under pressure through nozzles, simulating natural rainfall.
Step 2: Detailed Explanation:
A Raingun is a high-volume, high-pressure sprinkler device designed to discharge large quantities of water over a wide radius.
It operates at pressures ranging from $2$ to $7.5\text{ kg/cm}^2$ and can cover a circle of up to $40 - 100\text{ meters}$ in diameter.
Water is sprayed upward into the air, breaking into droplets that fall onto the crop canopy like natural rain.
Because it applies pressurized water through a nozzle into the air to simulate rainfall over a large area, the raingun system is classified as a specialized, high-capacity form of Sprinkler irrigation.
It is not related to drip irrigation (which applies water drop-by-drop to the root zone) or surface irrigation (which floods the soil surface).
Step 3: Final Answer:
The raingun irrigation system is a form of Sprinkler irrigation, corresponding to option (C).