The enthalpies of combustion of cyclohexane, cyclohexene and H2 are respectively −3920,−3800 and −241kJ mol⁻¹. The heat of hydrogenation of cyclohexene is:

A. 121kJ mol⁻¹
B. 242kJ mol⁻¹
C. −121kJ mol⁻¹
D. −242kJ mol⁻¹