Explanation: The relationship between the wavelength ($\lambda$) of an electromagnetic wave, its frequency ($f$), and the speed of light ($c$) is fundamental to radio theory. This relationship is expressed by the formula: $\lambda = c/f$. The speed of light ($c$) in a vacuum (and approximately in air) is approximately $3 \times 10^8$ meters per second (300,000,000 m/s). The given frequency ($f$) is 3 GHz, which is $3 \times 10^9$ Hertz (3,000,000,000 Hz). Plugging these values into the formula: $\lambda = (3 \times 10^8 \text{ m/s}) / (3 \times 10^9 \text{ Hz})$ $\lambda = 10^{-1} \text{ meters}$ $\lambda = 0.1 \text{ meters}$ To convert meters to centimeters, multiply by 100: $0.1 \text{ meters} \times 100 \text{ cm/meter} = 10 \text{ centimeters}$. Therefore, a RADAR operating at 3 GHz has a wavelength of approximately 10 centimeters. Options A, C, and D are incorrect calculations based on this fundamental relationship.