The correct answer is D) so as not to load down the circuit and obtain erroneous voltage readings. When troubleshooting electronic equipment, a high impedance multimeter is recommended to prevent loading down the circuit under test. A low impedance meter would draw excessive current from the circuit, potentially altering the voltage being measured and providing an inaccurate reading. By using a high impedance meter, the current drawn is minimized, allowing for a more precise voltage measurement without significantly affecting the circuit's operation. This is important to obtain reliable diagnostic information when troubleshooting electronic components and systems. The other options are incorrect because: A) A high impedance meter is recommended for both AC and DC measurements, not just AC. B) Using a high impedance meter is the preferred practice, not just when a low resistance meter is unavailable. C) Preventing damage to the meter is a secondary consideration, the primary reason is to avoid loading down the circuit.