GMAT Sentence Correction (SC) | Re: While market-driven competition encourages

First, eliminate C and D for saying twice as much by marketing than; E is out for distorting the original meaning. In addition, the format of 'as x as y' is not found in the choice.
Between A and B, A is wrong for comparing what marketing accounts for with research rather than what research does to match the action of marketing. B prevails.

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