The bolded sentences above are the explanation we were given to answer the question, but I am still confused. Can someone please explain this question in depth?

Heats of hydrogenation have been used to quantify the stabilization energy resulting from conjugation of double bonds. The two sets of reactions (3 compounds each) given below were carried out and conclusions were drawn as shown. a) Are both reactions error-free or is one (or both) flawed giving erroneous results? b) Why is this so? c) What approximate value of correct stabilization energy (in kJ/mol ) do you expect to find? d) In case one or both experiments are flawed, what amount of erroneous "stabilization" energy (in kJ/mol ) do you expect to find qualitatively, i.e. higher or lower than c)? The first reaction is okay. It will yield a stabilization energy of approximately 15 kJ/mol. The second reaction is flawed. Even though all proposed alkenes yield the SAME alkane upon hydrogenation, the alkene in the center is Z-configured ("cis"); however, the E-configuration ("trans") would be needed as a correct reference to the diene. Qualitatively, the erroneous "stabilization" energy will be larger than 15 kJ/ mol because " y " will yield a higher heat of hydrogenation due to its Zconfiguration (more strained)