Either high cholesterol or unbalance homocysteine levels can, along with elevated blood pressure, be factors contributing to the incidence of heart disease in this country.

(A) can, along with elevated blood pressure, be factors contributing to
(B) along with elevated blood pressure, can one or the other be contributing factors in
(C) can, along with elevated blood pressure, contribute as factors to
(D) can be a contributing factor to, along with elevated blood pressure
(E) can contribute, along with elevated blood pressure, to

Meaning : Out of the 2 factors ( high cholesterol or unbalance homocysteine levels ) can contribute to the incidence of heart disease in the country.

Contribute to : Correct Idiomatic Usage

Either high cholesterol or unbalance homocysteine levels can contribute, along with elevated blood pressure, to the incidence of heart disease in this country.

Further Either X or Y : Correct Idiomatic usage and is correctly used in option (E), thus Answer must be (E)

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Dear Sir,

Is answer option A grammatically correct?? it sure is not concise or succinct How do we eliminate option A

Good questions on (A). A couple things on (A):

1) The meaning there is off. If you look at the subject/verb setup, (A) says "either X or Y can be factors" (and then "contributing to..." qualifies what kind of factors) - this makes the fact that these conditions contribute to heart disease kind of an afterthought, vs. E which more directly says "they contribute to heart disease." The purpose of the sentence is to say that these conditions lead to heart disease...(A) kind of buries the headline by saying they're factors as the main thought, and then qualifying those types of factors also. (NOTE: A vs. E to me is a great example of why having five answer choices is a HUGE advantage vs. trying to edit a single sentence in isolation - I wouldn't necessarily see this meaning problem unless I compare A and E, but when I do I think "yeah that meaning in A is off").

Also "can be factors" puts the conditional "can be" in an odd spot - the conditional "sometimes but not always" isn't that these conditions could be factors, but that they could contribute to heart disease. "Can be factors" suggests that we don't know whether they're always factors...what we really don't know is whether these factors can cause heart disease.

Similarly the tense on "contributing" is off, too - that suggests that these are temporarily contributing to heart disease, but with scientific cause-and-effect, logically they either contribute to heart disease always, or they don't. There isn't a "during this limited period high cholesterol will cause heart disease, but after the summer solstice that won't be the case anymore" kind of thing. If it were "are factors that contribute" then we solve that problem by using a more definitive tense fitting of the scientific subject, but as written it's too temporary.

2) It's a tricky one but in an Either/Or construction, the singularity/plurality is dictated by the noun that comes after "or." And here although "levels" is plural, we're not really saying the levels themselves are what cause heart disease, but rather the state of them being unbalanced. You really should have "unbalanced homocysteine levels can be a factor," singular.

This is one that's pretty ugly - you wouldn't say "unbalanced levels is a factor" but rather "unbalanced levels are a factor"...as a test-taker what I love about E is that it just avoids the situation altogether. That's pretty classic GMAT - wrong answers introduce a really unique and odd structure, but instead of making you choose a unique grammatical structure, they give you an answer that just totally avoids it.
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