The correct answer is option 1, which arranges the tributaries from west to east as 2-4-3-1.

To understand why this is the correct answer, let`s look at the individual tributaries:

1. Lohit: As per option 1, Lohit is the first tributary listed. This means it is the westernmost tributary among the given options.

2. Tista: The next tributary listed in option 1 is Tista. This suggests that Tista is located to the east of Lohit.

3. Subansiri: Following Tista, Subansiri is listed as the third tributary. Therefore, Subansiri is situated further east than Tista.

4. Sankosh: In option 1, Sankosh is the final tributary listed, indicating that it is the easternmost among the given options.

Hence, by arranging the tributaries in the order 2-4-3-1, option 1 correctly represents the west to east direction of the tributaries of the river Brahmaputra.