The correct answer is A. ohms/°C.
The temperature coefficient of resistance is a measure of how much the resistance of a material changes with temperature. It is usually expressed in parts per million per degree Celsius (ppm/°C) or in micro ohms per ohm per degree Celsius (µΩ/Ω/°C).
The temperature coefficient of resistance is positive for most materials, which means that the resistance increases with increasing temperature. However, there are some materials, such as semiconductors, for which the temperature coefficient of resistance is negative. In these materials, the resistance decreases with increasing temperature.
The temperature coefficient of resistance is an important property of materials that are used in electrical circuits. For example, the temperature coefficient of resistance is used to design resistors that have a stable resistance over a wide range of temperatures.
The other options are incorrect because they do not express the temperature coefficient of resistance in a meaningful way. Option B, mhos/ohm°C, is not a unit of measurement that is used to express the temperature coefficient of resistance. Option C, ohms/ohm°C, is a unit of measurement that is used to express the resistivity of a material. Option D, mhos/°C, is a unit of measurement that is used to express the conductivity of a material.