What is enthalpy?
the total concentration of the system
the total heat content of the system
the total pressure of the system
the total internal energy of the system

Enthalpy is the total heat content of the system.

To add, Enthalpy is a measurement of energy in a thermodynamic system. It is the thermodynamic quantity equivalent to the total heat content of a system. Enthalpy is equivalent to the internal energy of the system plus the product of pressure and volume.

i'm wiling to try and you : )

i think it's letter a.