Explanation:

- Sonam Losoong (Option 2): The correct answer. Sonam Losoong is the traditional New Year celebration for the Sikkimese Bhutia, marking the end of harvest season and coinciding with the 10th month of the Sikkimese Lunar calendar.

- Ashura (Option 1): An Islamic observance falling on the 10th day of Muharram in the Islamic lunar calendar, significant for both Sunni and Shia Muslims due to historical and religious reasons.

- Vesak (Option 3): Celebrated by Buddhists worldwide, it marks the birth, enlightenment, and death of Buddha and generally falls in April or May.

- Thai Pongal (Option 4): A Tamil harvest festival dedicated to the Sun God, celebrated in January in Tamil Nadu and Sri Lanka.