TBR O-Chem 1 bond breaking question

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8. The GREATEST amount of energy is required to break which of the following carbon-carbon bonds?
A. H3C-CH3
B. (H3C)3C--C(CH3)3
C. H2C=CH2
D. (H3C)2C=C(CH3)2

I can somewhat deduce the correct answer (D.) from radical stability, but the textbook provides a Table that I'm having trouble correlating it to.

Table 2
Alkene enthalpy for hydrogenation
H2C=CH2 -32.6
R2C=CR2 -26.4

Is Table 2 stating that the unsubstituted alkene gives off more energy when hydrogenated than the fully-substituted one, and thus the reaction is more favorable in the case of the unsubstituted, so that double bound is easier to break? I want to make sure I understand because I feel like I'm having a bit of trouble differentiating between bond enthalpies and bond energies.

 

[HotHamH2O]

You are basically looking at the catalytic hydrogenation of an alkene. Catalytic hydrogenation is always negative and therefore, always exothermic. Heat of hydrogenation of alkene's is essentially a measure of the stability of the carbon-carbon double bonds. The smaller the numerical value of the reaction, the more stable the bond is. The more stable the bond is, the more energy it will release when it is finally broken. You order of stability is tetra > tri > di > mono. Remember also that alkyl groups donate electrons so they help with the stability of the bond partly due to the fact that they shorten it. In this problem, you just have to remember that if it releases more energy, it requires more energy (law of conservation of energy).

For MCAT just remember that shorter = stronger = harder to break = releases more energy.

If I missed anything or was off on anything please feel free to make corrections!