The correct option is A Nature of the material and temperature
difference.
Linear expansion of a solid because of heat depends upon nature of material and the temperature difference. In scientific terms, heat is an internal energy that flows from a system of relatively high temperature to one at a relatively low temperature. The internal energy itself is commonly called "heat." When this internal energy of a solid increases, depending on the nature of material the internal molecular vibration increases. Which in turn is responsible for linear expansion. The linear expansion of a given solid can be calculated according to the formula L=aL0T. Where L is the change in length, T is the change in temperature, 'a' is the coefficient of linear expansion, and L0 is the original length.