Explanation: To match impedances using a transformer, the turns ratio (N) is determined by the square root of the impedance ratio. The fundamental formula is N = √(Z_source / Z_load), where Z_source is the impedance looking into the transformer's primary side (from the source) and Z_load is the impedance on the secondary side (the load). Given a source impedance of 500 ohms and a load impedance of 10 ohms: N = √(500 ohms / 10 ohms) N = √(50) N ≈ 7.071 Rounded to one decimal place, the turns ratio is approximately 7.1 to 1. This indicates that the primary winding should have roughly 7.1 times more turns than the secondary winding to achieve the desired impedance match. Therefore, option A (7.1 to 1) is the correct turns ratio. Option B (7 to 1) is very close but not precise, as the square root of 50 is slightly greater than 7. Options C and D are incorrect based on this calculation.