In order to present an essay using chronological organization, you must organize the paragraphs in time order (A).
Chronological order means putting something in order based on the time in which it occured. The earliest event would go first and the most recent event would go last. Therefore, the only logical answer is that the paragraphs would go in time order. You might think the answer could be B because the details are also put in order. However, note that the details are put in order based on how they appear in process or illustration, not based on time.