Explanation: In the context of Tamil Nadu's geography and history, the term "historic" is used to describe events that are significant and impactful, often due to their unprecedented nature or the lasting effects they have on the region. The floods in December 2015 and Cyclone Vardah in 2016 are prime examples of such events.
The floods in December 2015 were one of the worst natural disasters to hit Chennai in recent history. The city experienced unprecedented rainfall, leading to severe flooding that caused significant damage to infrastructure, homes, and businesses. The event was so severe that it was described as a "once-in-a-century" event, highlighting its historical significance.
Cyclone Vardah, which struck Chennai in 2016, was another catastrophic event that had a profound impact on the region. The cyclone caused widespread destruction, with strong winds and heavy rainfall leading to extensive damage to buildings, trees, and power infrastructure. The cyclone was particularly devastating due to its intensity and the extent of the damage it caused, making it the worst cyclone in Chennai's history.
The term "historic" is appropriate in this context because it captures the unprecedented nature of these events and their lasting impact on Chennai. The floods and cyclone were not just dangerous or economically impactful; they were significant enough to be remembered and studied for their historical importance. The term "historic" conveys the idea that these events are part of Chennai's history and will be remembered for their severity and the changes they brought about in the region.
In summary, the floods in December 2015 and Cyclone Vardah are described as "historic" because they were unprecedented in their severity and had a lasting impact on Chennai. The term "historic" is the most appropriate choice among the given options as it accurately reflects the historical significance of these events.