Test 1 Section 2 - #4 (page 390)

Remember that sometimes the sentence comps say the same thing twice, with clues in one part and blanks in another, and your clues should be your anticipations.  I've bolded what I think your anticipations should be below:

"...a visceral decision rather than a rational judgment; that is, it was not so much rational as visceral." 

So you're looking for an answer with a rational...visceral pairing. Choice (D): "a deliberate...instinctive" fits that pairing very nicely.