There are flaws in the grammatical and meaning of the answer choice. I only discuss B and E.
1) B is
grammatically wrong because "due to" is an adjectival prepositional phrase, only modifies noun/ noun phrase and should come after verb "to be".
Thus, "due to" cannot modify the whole clause "SIDS likely occurs more"
2) E is
wrong in the meaning, pointed out by Dimitry.
It is not because the infants exhibit high levels but because the high levels themselves that leads to the claim that "SIDS likely occurs"
The question answers are not good. When I study and see such sentences, I just get angry because I feel empathy with those who studies in a decent way and gets bewildering answers (Surely I feel sympathy with myself too

)
DmitryFarber
"Due to" isn't wrong in itself. It basically means the same thing as "because of." SIDS doesn't occur because of "the fact that" high levels of hemoglobin are found, so (A) is out. It also doesn't occur because of these levels "being found," so (B) is out.
However, the credited response of (E) is not significantly better. We should say that the high levels cause SIDS, not that it occurs because the infants
exhibit high levels.