ANS:C - entropy

When a solid is compressed adiabatically in its elastic range, its temperature remains constant. This is because an adiabatic process is one in which there is no heat exchange with the surroundings. In the case of adiabatic compression, the work done on the solid increases its internal energy. However, since there is no heat transfer, the increase in internal energy solely results in an increase in temperature. Entropy, on the other hand, is a measure of the disorder or randomness in a system. In an adiabatic process, entropy can change if there are changes in other factors, such as volume or pressure, but it is not directly related to the temperature remaining constant during adiabatic compression of a solid in its elastic range. Therefore, I apologize for the incorrect answer provided earlier. The correct answer is temperature, as it remains constant during adiabatic compression of a solid in its elastic range.