The correct answer is option 4, March-April. This is because tropical cyclones in the Bay of Bengal are most frequent during the months of March and April.
Option 1, October-November, is incorrect because this period is actually the post-monsoon season, when the weather conditions in the Bay of Bengal are generally calm.
Option 2, May-June, is also incorrect because this period marks the beginning of the Southwest monsoon season, when the Bay of Bengal experiences heavy rainfall but not necessarily tropical cyclones.
Option 3, January-February, is incorrect as well because this period is during the Northeast monsoon season, when the frequency of cyclones is generally lower compared to March-April.
Overall, understanding the seasonal patterns and weather conditions in the Bay of Bengal helps identify the most likely time for the occurrence of tropical cyclones.