The correct answer is: b) Limited passenger ferries.
The Brahmaputra River is the longest river in India and the third longest river in Asia. It is navigable for limited passenger ferries, but not for large cargo ships. The river is too shallow and has too many rapids for large ships to navigate. However, it is possible to travel by ferry on the Brahmaputra River between some of the towns and villages along its banks.
Option a) is incorrect because the Brahmaputra River is not navigable for large cargo ships. The river is too shallow and has too many rapids for large ships to navigate.
Option b) is correct because the Brahmaputra River is navigable for limited passenger ferries. However, it is not possible to travel by ferry on the Brahmaputra River between all of the towns and villages along its banks.
Option c) is incorrect because the Brahmaputra River is navigable for limited passenger ferries.
Option d) is incorrect because the Brahmaputra River is navigable for limited passenger ferries, but not for large cargo ships.