Critical Reasoning (CR) | In a study of office workers at a corporation, Australian researchers

C should be the answer.
The conclusion is "work breaks ( can be any sort I.e going for a tea break or surfing internet etc ) are rejuvenating .
The premise cited is :- One example where the workers browsing internet proved more productive than the workers who abstained from internet.
Option C strengthens by saying that the workers who abstained from internet not just stayed away from the internet but dint indulge in too many other forms of breaks also. They took far fewer breaks. And eventually they proved less productive. Hence the conclusion i.e "work breaks are helpful in increasing productivity and rejuvenating " gets strengthened.

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