Whereas in mammals the tiny tubes that convey nutrients to bone cells are arrayed in parallel lines, in birds the tubes form a random pattern.

Option A
Option B
Option C
Option D
Option E

(This question is from Official Guide. Therefore, because of copyrights, the complete question cannot be copied here. The question can be accessed at GMAT Club)

Solution

Sentence Analysis

• Whereas
  • in mammals the tiny tubes
    • that convey nutrients to bone cells
  • are arrayed in parallel lines,
• in birds the tubes form a random pattern.

The sentence presents a contrast between the way the tubes are arranged in mammals and the way they are arranged in birds. In mammals, they are arrayed in parallel lines, and in birds, they form a random pattern.

There is no error in the sentence. The contrast is explained clearly with a parallel structure:

• In mammals, the tiny tubed are arrayed in parallel lines
• In birds, the tubes form a random pattern

Option Analysis

(A) Correct.

(B) Incorrect. This option has the following errors:

1. “tiny tubes for the conveying of nutrients” distorts the original meaning “tiny tubes that convey nutrients”. Saying “tubes for the purpose of xyz” is very different from saying “tubes that do xyz”. In the latter construction, it is quite clear that tubes perform xyz whereas in the former construction, it seems that tubes are used for the purpose of xyz but not clear what exactly is their function.
2. The presence of two “in” phrases — “in mammals” and “in parallel lines” — together makes the sentence awkward compared to the original sentence.
3. The option distorts the contrast. Now, the contrast illogically seems to be between “tiny tubes are arrayed in mammals in parallel lines” and “birds have tubes”.

(C) Incorrect. This option has the following errors:

1. “where”, a word that must refer to a physical location, refers to mammals.
2. “tiny tubes for conveying nutrients” – Same error as in option B.
3. The structure of the option is “Unlike mammals – modifier for mammals – birds’ tubes”. So, the option draws an illogical comparison between mammals and birds’ tubes.

(D) Incorrect. This option draws an illogical comparison between mammals and the tubes in birds.

(E) Incorrect. This option has the following errors:

1. The option completely distorts the meaning. Now, it seems that the bone cells, not the tiny tubes, are arrayed in parallel lines. Rather, from this option, we cannot say that we are specifically talking about tiny tubes in mammals. It seems that we are talking about tiny tubes in general.
2. The comparison is ungrammatical. In “Unlike X, Y”, both X and Y need to be nouns or pronouns. In this option, Y is a prepositional phrase “in birds”