The conclusion of the stimulus is the last sentence. It’s important to note the conditional language in it. “…it needs to have a clear time frame and be no more than 30 minutes longâ€
This “needs†is introducing a necessary condition.
A) Converse, or mistaken reversal of the conclusion. The conclusion says a clear time frame and 30 minute maximum are necessary for a meeting to achieve maximum productivity, but answer choice A treats these conditions as if they are sufficient to guarantee maximum productivity.
C) Correct, because it introduces these conditions (clear time frame and 30 minute max) as necessary to a maximally productive meeting by saying “only if.â€