The correct answer is - The southwest monsoon from the ocean.
The southwest monsoon air masses are moving over the Indian Ocean, get warm and wet, and when they reach the land of South Asia, they bring in huge amounts of precipitation.
These monsoons, in fact, bring in the largest amounts of precipitation in the world, with all of the places that have the highest annual precipitation being in India. Because the amount of rain is so big, there's lot of floods across South Asia, with the worst being in Bangladesh, because the country is very low, so almost half f it is under water when the southwest monsoons are in action.
