What did the saperas use to carry their snakes? 

Saperas are snake charmers whose source of livelihood is playing their flutes or been to make the snakes dance and sway to the music. They travelled from village to village with their snakes in a bamboo basket, showing their powers over the snakes. So option B is correct. Using jute bags for carrying snakes would be uncomfortable for the reptiles and a carton box is not suitable as it has no holes for air passage. Bamboo baskets have tiny holes which allow the reptiles to breathe even when the basket's lid is closed.