If standard enthalpies of combustion of CHOOH ,graphite(s) and H₂(9) are−700,−400 and −300 kJ J mol⁻¹ then standard enthalpy of formation of CH₃OH will be

a. −600 kJ mol ⁻¹
b. 300 kJ mol⁻¹
c. 600 kJ mol⁻¹
d. −300 kJ mol⁻¹