The correct answer is C. Carbon.
A material with a negative temperature coefficient of resistance (NTCR) is one whose electrical resistance decreases as the temperature increases. This is in contrast to materials with a positive temperature coefficient of resistance (PTCR), whose resistance increases as the temperature increases.
Carbon is a semiconductor, which means that its electrical conductivity is between that of a conductor and an insulator. The conductivity of semiconductors increases with temperature, which is why carbon has a negative temperature coefficient of resistance.
Copper, aluminum, and brass are all conductors, which means that their electrical conductivity is relatively high. The conductivity of conductors decreases with temperature, which is why copper, aluminum, and brass have a positive temperature coefficient of resistance.
In conclusion, carbon is the only material listed that has a negative temperature coefficient of resistance.