Cp is the change in enthalpy with respect to temperature at constant

Cp is the change in enthalpy with respect to temperature at constant _____________

A. Pressure

B. Volume

C. Temperature

D. None of the mentioned

I got this question in unit test.

This intriguing question comes from Enthalpy in chapter Energy Balances of Chemical Process Calculation

The correct option is A. Pressure

To explain I would say: Cp is the change in enthalpy with respect to temperature at constant Pressure.