Explanation: To determine the power dissipated by a resistor, we use the formula P = I$^2$R, where P is power in watts, I is current in amperes, and R is resistance in ohms. This fundamental relationship, often called Joule's Law, is critical in amateur radio for calculating component stress and ensuring proper circuit design. Given: Current (I) = 0.25 A Resistance (R) = 20 ohms Applying the formula: P = (0.25 A)$^2$ * 20 ohms P = 0.0625 A$^2$ * 20 ohms P = 1.25 watts Therefore, the resistor dissipates 1.25 watts. Understanding power dissipation is essential for selecting components that can handle the heat generated in a circuit, preventing damage and ensuring reliable operation. Options A, B, and C result from incorrect application of power formulas.