The correct answer is A. Manganin.
Manganin is an alloy of copper, manganese, and nickel. It has a very low temperature coefficient of resistance, which means that its resistance changes very little with changes in temperature. This makes it a good material for use in electrical resistance wire, such as in rheostats and potentiometers.
Porcelain is a ceramic material made from clay and other minerals. It has a high temperature coefficient of resistance, which means that its resistance changes a lot with changes in temperature. This makes it a poor material for use in electrical resistance wire.
Carbon is a non-metallic element. It has a high temperature coefficient of resistance, which means that its resistance changes a lot with changes in temperature. This makes it a poor material for use in electrical resistance wire.
Copper is a metallic element. It has a low temperature coefficient of resistance, which means that its resistance changes very little with changes in temperature. This makes it a good material for use in electrical wiring and other applications where a stable resistance is important.
In conclusion, the correct answer is A. Manganin.