Sentence Correction

Hi,

In relation to another post that I wrote, I would like to provide more detail to explain my question related to parallelism and comparisons. Let's see the following sentences in the OG12th:

135.

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.


(A) Whereas in mammals the tiny tubes that convey nutrients to bone cells are arrayed in parallel lines, in birds the tubes (OA)


(B) Whereas the tiny tubes for the conveying of nutrients to bone cells are arrayed in mammals in parallel lines, birds have tubes that

Here, the OE indicates that, in choice B, "tubes" is not logically parallel with "birds". I agree with that. But notice that both "tubes" and "birds" are subjects in their clauses. So, it seems that when we analyze whether the elements compared are parallel we have to analyze the subjects. Also, I think that it is important to compare the subjects because they answer the question about who we are talking about in each clause.

Now let's see the following question:

131.

Over 75% of the energy produced in France derives from nuclear power, while in Germany it is just over 33%.

OA is:

C) whereas nuclear power accounts for just over 33% of the energy produced in Germany

Ok, now let's compare the subjects in the clauses of the OA and the part that is not underlined: ¿" % of the energy produced in (a country) vs. "nuclear power"? If we used the logic of the other question, this last sentence would not be correct. The compared subjects are not parallel. It's like we would be comparing apples and oranges. How can this be the OA?

Ok, probably, someone can say that I shouldn't compare only the subjects but the entire idea of each clause.

Well, if we used that logic, obviously choice C in the last question would be correct. But if we used that logic in the first sentence (#135) (just compare ideas and not only the subjects), I think that choice B would be also correct. In choice B, the subjects are not parallel but the ideas in both clauses are clear; we understand that mammals have tiny tubes which are parallel, while birds have tubes that form a random pattern. How cannot that choice be correct? Ok, probably B is not correct because it is awkward. But if choice A (the OA) did not exist, would choice B be correct?

In summary, how can I solve this apparent contradiction. How can I know when compare the subjects or when compare the whole idea of each clause. Simply, I don't understand it :s