The reaction C₂H₆+137kJ→C₂H₄+H₂ is endothermic since the energy is being absorbed by the reaction and not released. We know this by the fact that the energy is on the reactants side of the reaction. If the energy was on the products side of the reaction we would call it exothermic since energy would be being released. Since this reaction is endothermic we know that the products will have more energy than the reactants which means that the answer is B.
(the equation in the question does not have an arrow in it so I assumed it was between the 137kJ and C₂H₄).
I hope this helps. Let me know if anything is unclear.
