Although improved efficiency in converting harvested

[AnupamaS757]

Hi experts,
Can you please throw some light on what would be the correct answer for the following question? I came across it somewhere where it says its gmatPrep question but I am not convinced as the OA is debatable so I am posting here.

Although improved efficiency in converting harvested trees into wood products may reduce harvest rates, it will stimulate demand by increasing supply and lowering prices, thereby boosting consumption.

A. in converting harvested trees into wood products may reduce harvest rates, it will stimulate demand by increasing supply and lowering prices, thereby boosting

B. in converting harvested trees into wood products may reduce harvest rates, demand will be stimulated because of increasing supply and lowering prices, which boost

C. of converting harvested trees into wood products may reduce harvest ates, it will stimulate demand by increasing supply and lowering prices which boosts

D. of harvested trees being converted into wood products may reduce harvest rates, it will stimulate demand, because it will increase supply and lower prices, thereby boosting

E. when harvested trees are converted into wood products may reduce harvest rates, demand will be stimulated because of increasing supply nd lowering prices, which boost

My take:
A: Suspicious of "it" referring to efficiency . Also, "boosting" modifying preceding clause action, "stimulating demand" does not look correct to me. But this is 2nd best choice for me after D.
B,E : "because of increasing supply and lowering prices" looks wierd to me....According to me, "because of" should be followed by Noun/Noun phrase
C: "which boosts" is incorrect because even if we take just "prices", it should be plural as well.
So, I think answer should be D.

[Sage Pearce-Higgins]

Where did you come across this question? There are lots of poor quality GMAT resources out there, so take care not to waste your time.

Here's how I'd tackle the problem:
Split number 1: 'efficiency in' vs. others. 'Efficiency when' is clearly wrong, as 'when' must refer to a time (eliminates E). 'Efficiency of' has a meaning that isn't appropriate here: we'd talk about the efficiency of a car or a machine, but when discussing a process, 'in' is the correct idiom.
Split number 2: 'thereby boosting' vs. 'which boost'. Since we're talking about a consequence here, the 'comma - ing' modifier is more appropriate. Furthermore, 'demand will be stimulated because of' is incorrect, it should be 'demand will be stimulated by'.

I think the correct answer is A.