During a collision, the quantities that remain constant are

According to the law of conservation of momentum, the total momentum of an isolated system remains constant during any type of collision (elastic or inelastic), provided no external force acts on it.

Kinetic energy is not conserved in inelastic collisions, as a portion of it is converted into other forms of energy such as heat, sound, or internal energy. Even in perfectly elastic collisions, kinetic energy is not constant during the actual time of impact because some of it is temporarily converted into elastic potential energy of deformation.

The conversion of kinetic energy into heat energy in inelastic collisions leads to an increase in the internal energy, which changes the temperature of the system. Thus, temperature does not remain constant.

Therefore, only momentum remains constant during a collision, but neither kinetic energy nor temperature.