Option 1 is not correct as Yamuna and Yarlung Zangbo are alternative names for the river but Tsangpo is not.

Option 2 is not correct as Megna is not an alternative name for Brahmaputra.

Option 3 is partially correct as Jamuna, Siang, Yarlung Zangbo, and Tsangpo are alternative names for the river Brahmaputra.

Option 4 is the correct answer as it includes all the alternative names for the Brahmaputra river, which are Jamuna, Siang, Yarlung Zangbo, and Tsangpo.

The Brahmaputra river is known by different names in different regions along its course. In India, it is called the Jamuna in its lower reaches, while in Arunachal Pradesh, it is known as Siang. In Tibet, China, it is called the Yarlung Zangbo, and in the upper reaches of the river, it is known as the Tsangpo.