Final answer:
The appearance of Halley’s comet every 76 years is the best example of a cyclic event because it occurs at regular and predictable intervals, unlike unpredictable natural disasters such as hurricanes, earthquakes, and tsunamis. Therefore, the correct answer is a.
Step-by-step explanation:
The best example of a cyclic event among the options provided is the appearance of Halley’s comet every 76 years. This is because it is an event that occurs at regular and predictable intervals, which is the defining characteristic of a cyclic event. Hurricanes, earthquakes, and tsunamis are natural disasters that can be recurrent, but they are not predictable in the same cyclic manner as celestial events like comets. Hurricanes and other weather phenomena may have a season when they are more likely to occur, but each event is unique and not as predictable as the return of a comet.