GMAT Critical Reasoning (CR) | Re: Properly measuring the efficiency of manufacturing equipment

Thanks for the response sayantanc2k! The addition of 'only' will definitely change things a lot. But tell me, don't you think option D could've been better stated as "The only factor relevant to measuring the EFFICIENCY of manufacturing equipment is NOT the productivity of such equipment."? Don't you think the objection raised i.e. "Does higher productivity imply higher efficiency? What if the quality of all the foam concrete produced by this equipment is inferior?" hints more
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