Since delta H is negative, that means that heat is released, so that eliminates two answers. Since the second response says that twice the delta H value is released for every mole of H2O, that mean that there would have to be a coefficient of 2 in front of H2O for that statement to be true. The next response says that half of the delta H value is released when half of CaO reacts. Since this response is consistent in that if an entire mole of CaO reacts, then the full delta H value would released. So the third response is correct
