Specific enthalpy is a thermodynamic property that represents the total energy contained in a substance per unit mass. It is defined as the sum of the internal energy and the product of pressure and volume. The SI unit for specific enthalpy is Joules per kilogram (J/kg).

- Explanation of Specific Enthalpy:
Specific enthalpy (h) is a measure of the energy content per unit mass of a substance. It takes into account the internal energy (u) and the work done (Pv) by the substance. The internal energy represents the energy stored in the molecular structure of the substance, while the work done represents the energy transferred to or from the substance due to pressure and volume changes.

- SI Unit for Specific Enthalpy:
The SI unit for specific enthalpy is Joules per kilogram (J/kg). This means that the specific enthalpy of a substance is measured in terms of the amount of energy (in Joules) contained in each kilogram of the substance. It is important to note that enthalpy is an extensive property, meaning that it depends on the amount of substance present.

- Comparison with other Units:
Option 'A' states Pascal as the unit for specific enthalpy. Pascal (Pa) is the SI unit of pressure and does not represent specific enthalpy.

Option 'B' states Newton per meter as the unit for specific enthalpy. Newton per meter (N/m) represents the unit of a force per unit length and is not the correct unit for specific enthalpy.

Option 'C' states Joules per kilogram as the unit for specific enthalpy. Joules per kilogram (J/kg) is the correct SI unit for specific enthalpy, as explained earlier.

- Conclusion:
The specific enthalpy is a thermodynamic property that represents the total energy contained in a substance per unit mass. The SI unit for specific enthalpy is Joules per kilogram (J/kg), which accurately reflects the amount of energy contained in each kilogram of the substance.