The answer is either 1. Mango or 4. Jack Fruit, depending on whether it means the tree itself or the edible food.
The mango is the national fruit of India. It is also the national tree of Bangladesh. In India, harvest and sale of mangoes is during March-May and this is annually covered by news agencies. The mango has a traditional context in the culture of South Asia.
Bangladesh is a tropical country that provides favorable growing conditions for many fruits, including mango, pineapple, and bananas. The national fruit of Bangladesh is the jackfruit, and the abundance is perhaps the reason why it is the national fruit.