Which of the following is true?

• A.Standard enthalpy change of combustion is the enthalpy change when two moles a substance is completely ashed in nitrogen
• B.Standard enthalpy change of combustion is the enthalpy change when one mole of the substance. is burnt completely in oxygen under standard conditions
• C. Standard enthalpy change of combustion is the enthalpy change when one mole of oxygen and methane are liquefied in Nitrogen under standard conditions
• D.Standard enthalpy change of combustion is enthalpy change when one mole of oxygen reacts endothermically with other substances under standard conditions