GMAT Critical Reasoning (CR) | Antibiotic Resistance (New CR Question from OG 016)

I usually focus on the conclusion while selecting the correct answer. The conclusion on this question is failure to take medication (cause) led to sinus infection(effect). So I looked for an answer choice that supports this cause -effect relationship. But, the correct answer states the cause of the failure to take medication and not that failure to take medication resulted in sinus infection. i missed the answer choice due to this thought process.Is there something wrong in my approach?

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