For image magnification, one needs at least

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Nichrome

Copper

Silver

Manganin

answer is A.

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Detailed Solution

Concept: Resistance is a property of a material that resists the flow of charge to itself. Resistance is defined as voltage vs. current.
The optimum resistance is a resistance that is stable and does not change in value (when using a non-variable circuit) . To do this, the resistor must be made of a material that is not affected by temperature, has a low temperature coefficient, and has high resistivity. The best option is Manganin. This is because manganin as a material has all of the above properties. The more stable the resistance in the circuit, the more stable the circuit will be, and the above characteristics are required. The more stable the circuit, the better, the longer it works, and the more it needs to be. Manganin and nichrome are alloys (composed of a combination of metals) , and copper and silver are pure metals. Here the manganin is more stable as well as heat resistant than nichrome. Other materials also show some properties needed to make a standard resistor, but they did not have all the properties.
Hence , the correct choice is 4.

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