The most prominent characteristic of High-performance

The most prominent characteristic of High-performance marketing firms is that they have a tendency to have concentrated greater executives in the direction of a smaller, more careful selection of a number of important businesses than is the case with other marketing firms.
A) that they have a tendency to have concentrated greater executives in the direction of a smaller, more careful selection of a number of important businesses than is the case with
- Completely awkward, Illogical, Incorrect placement of Adjective

B) that they tend to concentrate more executives to a smaller, more careful selection of a number of important businesses than toward
- Although this option is not ambiguous but the use of "TO" is incorrect

C) that they have a tendency to concentrate more executives on a smaller, more careful selection of a number of important businesses as opposed to -
This option is ambiguous in meaning: moreover use of MORE is also confusing

D) that they tend to concentrate more executives on a smaller, more carefully selected number of important businesses than do - CORRECT

E) the tendency to concentrate a greater number of executives on a careful and small selection of a number of important businesses as opposed to -
THAT is Necessary otherwise it will change the meaning to "characteristic of X is their tendency". Completely illogical

Thus the answer has to be D & it is definitely a 700+ level question

Hope this explanation helps.
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