Answer: Choice D
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Reason:
Replace n with 1 in choice A to get
Choice A says the first term is 11, but this contradicts the fact that the first term should be -7 instead. Therefore, we cross choice A off the list.
You should find that choice B is the exact same story, so it must be eliminated as well.
Choice C has n = 1 get us
which is close, but we want the result to be negative 7 instead of positive. Choice C is eliminated as well.
The only thing left is choice D. Sure enough, plugging in n = 1 does lead to the first term of -7. If you tried n = 2, then it would get you -1 as the second term, and so on. This confirms choice D is the correct answer.