A, according to the image, when the nuclei combine into atoms, the total mass of the nuclei decreases, and mass defect exists, thus releasing nuclear energy, so A is correct;

B, according to the image, light nuclear fusion will have quality defects and release nuclear energy, so B is correct;

C, from the image, heavy nuclear fission has quality defects, to release nuclear energy, so C is correct;

D, as can be seen from the image, when the medium-mass nucleus decomposes the light nucleus, the mass increases and it needs to absorb heat, so D is wrong;

This question is wrong.

So choose D.