Explanation:

- Option 1: Zaskar

- Zaskar is a tributary of the Indus River.

- It flows in the northern part of India, joining the Indus at a point in Ladakh.

- Option 2: Nubra

- Nubra River is a tributary of the Shyok River, which itself is a tributary of the Indus River.

- Originating in the eastern Karakoram Range, it merges with the Shyok before ultimately contributing to the Indus River.

- Option 3: Shyok

- The Shyok River is a direct tributary of the Indus.

- Its confluence with the Nubra River eventually leads to it joining the main Indus River.

- Option 4: Lohit

- Lohit is not a tributary of the Indus River.

- It is a tributary of the Brahmaputra River, flowing through the Indian state of Arunachal Pradesh.