A is the best concise option here directly modifying countries. I think D is just the wordy version of A.

IMO: A

So-called green taxes, which exact a price for the use of polluting or nonrenewable fuels, are having a positive effect on the environment and natural resource base of countries as varied as China, the Netherlands, and Hungary.
A) as varied as
B) as varied as are
C) as varied as those of
D) that are as varied as
E) that are varied as are

The correct answer is between A and D. I would go for the option A.

D is also not wrong, but its just that option A is much better option claiming no requirement for the 'that'. a bit confusing...

Even option C is closer by the way. If the natural environment and the resource base is compared, then option C is the best option. But here the clear comparison is between the countries and not something else. In a comparison sentence always ask what is being compared.

Hope this helps...

Exactly. A and D are expressing the same idea, but A uses fewer words to do so. Brevity is important.

Bill what do you think of the option C. Could you please explain me why the answer cannot be C.

I actually saw this one the last time I took GMATPrep #1, and C looked best to me at first. However, the use of "those of" makes the comparison between the "environment and natural resource base" rather than between the countries themselves.

Bill that is what is confusing me as well. I am usually very good in Comparisons questions, but this one am not able to identify that whether the comparison is done between the countries or the environment and the resource base of those countries.

Honestly Both the comparisons seem correct to me.

In this case, I'd err on the side of the original. The comparison "as varied as" is next to "countries," so it is pretty safe to say that the comparions is between the countries. I can see what you're saying, though, and as I mentioned C was tempting to me as well.

Can across this problem on manhattangmat discussions.

https://www.manhattangmat.com/forums/so- ... -t351.html

Ron had earlier stated this example. D changes the meaning of the sentence. An example similar to what is being discussed here.

I get mail from cities as far away as Providence (Similar to A's structure)

I get mail from cities that are as far away as Providence (similar to D)