The enthalpy change for the reaction $2\mathrm{CO}\left(\mathrm{g}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)\to 2{\mathrm{CO}}_2\left(\mathrm{g}\right)$is termed as

Given reaction , suggests that two molecules of carbon dioxide combine with one to create two moles of
Since 
(i) the energy change in a reaction that creates 1 mole of any species is known as the enthalpy of creation 
The energy change in a reaction during the combustion of 1 mole of any species is known as the enthapy of combustion
The energy change in a reaction during the combustion of 1 mole of any species is known as the enthapy of combustion 
(ii) Enthalpy of fusion is the energy involved in fusion reaction of 1mole of any species.
Enthalpy of reaction
(iii) is the change in energy in any reaction. 
Therefore,
 option A is the correct response.