GMAT Critical Reasoning (CR) | Re: Internal professional sound processing boards offer sound engineers

I vote for C . Took 3 min. *(I wonder how to reduce time for such a big stimulus to comprehend especially for non-natives.)
A - weakener
B - Irrelevent.
C - hold it. because it says speed is not as important as this new modification. negating this case destroys the conclusion.
D - Irrelevent.
E - So what Irrelevent .

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