Identify the characteristics of an adiabatic process in a monoatomic gas.
(A) Internal energy is constant.
(B) Work done in the process is equal to the change in internal energy.
(C) The product of temperature and volume is a constant.
(D) The product of pressure and volume is a constant.
(E) The work done to change the temperature from $T_{1}$ to $T_{2}$ is proportional to $\left(T_{2}-T_{1}\right)$.
Choose the correct answer from the options given below :