The correct option is October and November.
Explanation
The climate of India is characterized by distinct seasonal rhythms. The Indian Meteorological Department (IMD) recognizes four distinct seasons, one of which is the season of the Retreating Monsoon, also known as the Transition Season. This period marks the withdrawal of the Southwest Monsoon winds and the gradual onset of winter conditions.
Detailed Analysis:
- October and November: These months constitute the season of the Retreating Monsoon. During October and November, with the apparent movement of the sun towards the south, the monsoon trough or the low-pressure trough over the northern plains becomes weaker. This is gradually replaced by a high-pressure system. The south-west monsoon winds weaken and start withdrawing gradually. By the beginning of October, the monsoon withdraws from the Northern Plains.
- Weather Characteristics: The retreat of the monsoon is marked by clear skies and a rise in temperature. While days are warm, nights are cool and pleasant. The land is still moist. Owing to the conditions of high temperature and humidity, the weather becomes rather oppressive during the day. This is commonly known as October Heat.
- Comparison with other options:
- September: While the withdrawal begins in northwestern India in September, the distinct season of retreat across the subcontinent is defined by October and November.
- December and January: These months characterize the Cold Weather Season (Winter).
Key Takeaway:
The months of October and November are officially recognized as the season of the Retreating Monsoon, serving as a transition period between the hot rainy season and the cold dry winter.