Which of the following statements is true?

a$.$ The change in internal energy of an ideal gas can be calculated using the equation $d{U}_{?}=CpdT,$ even if the pressure of the gas isn't constant.

b$.$ The change in enthalpy of a supercritical fluid can be calculated using the equation $dH=CpdT,$ even if the pressure of the fluid isn't constant.

c$.$ The expression $Cp=CV+R$ was derived for ideal gases, but is frequently applied to liquids and solids as well.

d$.$ The properties tabulated in the steam tables are all state properties, but none of them are extensive properties.

e$.W_{EC}=-PV,$ so $U-W_{EC}$ is equal to $H.$