Sentence Correction

Two new studies indicate that many people become obese more due to the fact that their bodies burn calories too slowly than overeating.

(A) due to the fact that their bodies burn calories too slowly than overeating
(B) due to their bodies burning calories too slowly than to eating too much
(C) because their bodies burn calories too slowly than that they are overeaters
(D) because their bodies burn calories too slowly than because they eat too much
(E) because of their bodies burning calories too slowly than because of their eating too much

The OA is D.

I know the coorrect option is D. But, why A is wrong?