Arteriviruses are a genus of microorganisms that cause digestive and

Can someone please explain why "that" is modifying "microorganisms" and not "genus" in A?

dabhishek87 We can use meaning to help with that. What's causing infections: the genus or the microorganisms? The genus itself can't cause infections, so the modifer has to apply to microorganisms.

In option D ; digestive and respiratory modify infections. so this part of sentence seems correct.

"which" is used for non essential modifiers . in this sentence if we remove 'which modifier' then the meaning of the sentence is lost.

so option A is correct.

Daag sir , pls. comment

Hi Experts, @gmatninja, @gmatninjatwo, @mikemcgarry,

In option B, is the parallelism correct in the "in humans and other mammals, and in birds"

I believe since humans are mammals, this parallelism makes more sense.

Please confirm if "in X and Other X's, and in Y's" is correct in the placement of comma before the second and

Thanks

Arteriviruses are a genus of microorganisms that cause digestive and respiratory infections, sometimes benign and sometimes severe, in humans, other mammals, and birds.

(A) Arteriviruses are a genus of microorganisms that cause digestive and respiratory infections, sometimes benign and sometimes severe, in humans, other mammals, and birds.

(B) Arteriviruses are a genus of microorganisms that causes digestive and respiratory infections, sometimes benign and sometimes severe, in humans and other mammals, and in birds. causes is singular and microorganisms is plural

(C) Arteriviruses are a genus of microorganisms that cause digestive and respiratory infections that are sometimes benign and sometimes severe, in humans, other mammals, and in birds. does not maintain parallelism. Should either be 'in X, Y and X or in X, in Y and in Z

(D) Arteriviruses are a genus of microorganisms, which cause digestive and respiratory infections that are sometimes benign and sometimes severe, in humans, other mammals, and birds. which correctly refers to microorganisms but it alters the meaning of the sentence. It says sometimes severe in humans, other mammals and birds. Both benign and severe needs to refer to humans, mammals and birds.

(E) Arteriviruses, a genus of microorganisms, cause digestive and respiratory infections, sometimes benign and sometimes severe, in humans, other mammals, and in birds.same as option C

Therefore, A is correct.

Yes, the paralllelism could be considered the way you mentioned. However the comma before "and" would have to be eliminated in that case. ["X, and Y" is not correct (except when X and Y are independent clauses) - "X, Y, and Z" is alright though (here the comma is optional).]

E not just has parallelism error but it has a meaning error as well. As per E Arteriviruses cause digestive and RI but as per original choice microorganisms cause digestive and RI

Arteriviruses, a genus of microorganisms, cause digestive and respiratory infections

I trap myself because I thought humans and mammals are the same; I have read somewhere about the relation between humans and mammals.

Arteriviruses are a genus of microorganisms that cause digestive and respiratory infections, sometimes benign and sometimes severe, in humans, other mammals, and birds.

(A) Arteriviruses are a genus of microorganisms that cause digestive and respiratory infections, sometimes benign and sometimes severe, in humans, other mammals, and birds.

(B) Arteriviruses are a genus of microorganisms that causes digestive and respiratory infections, sometimes benign and sometimes severe, in humans and other mammals, and in birds.

(C) Arteriviruses are a genus of microorganisms that cause digestive and respiratory infections that are sometimes benign and sometimes severe, in humans, other mammals, and in birds. (unparallel structure)

(D) Arteriviruses are a genus of microorganisms, which cause digestive and respiratory infections that are sometimes benign and sometimes severe, in humans, other mammals, and birds.

(E) Arteriviruses, a genus of microorganisms, cause digestive and respiratory infections, sometimes benign and sometimes severe, in humans, other mammals, and in birds. (the modifier cannot be left out + unparallel structure)

between A and B, the better choice is A b/c gmat tends to have a clear, direct, unambiguous, simple structure like the one in A.

VERITAS SOLUTION
Probably the easiest decision point to assess first is the obvious subject-verb agreement choice between "cause" and "causes". Since that relative clause is modifying microorganisms (not genus!) the verb must be the plural "cause." This allows you to eliminate (B) and (C). Then note the other important decision point in many of these answer choices - the list at the end of the sentence. Choices B, C, and E, all improperly list the three items that should be in parallel form: in humans, other mammals, and birds so (E) can also be eliminated. And choice D illogically assigns "which cause digestive and respiratory infections" to all microorganisms, when the point of the sentence is to show that this particular type of microorganism, the arterivirus, is what causes those problems. Choice A commits none of these errors, and is correct.

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