Which of the following is a tributary of river Indus?

The correct answer is Shyok.

To understand why Shyok is the correct choice, let us examine the river Indus and its major tributaries, and compare them with the other options provided:
1. Indus River and its Tributaries: The Indus River is one of the longest rivers in Asia. It flows through China (Tibet), India (Ladakh), and Pakistan. Its major tributaries include:
- Right Bank Tributaries: Shyok, Gilgit, Kabul, Kurram, Gomal, and Zhob.
- Left Bank Tributaries: Zanskar, Panjnad (which is formed by the five rivers: Jhelum, Chenab, Ravi, Beas, and Sutlej).
The Shyok River originates from the Rimo Glacier in the Karakoram range and flows through northern Ladakh before joining the Indus River. Therefore, it is a direct tributary of the Indus.

Let us analyze the other options to understand why they are incorrect:
2. Lohit and Dibang: Both of these rivers are major tributaries of the Brahmaputra River, not the Indus. They flow through the northeastern state of Arunachal Pradesh and Assam.
3. Betwa: The Betwa River is a tributary of the Yamuna River (which in turn is a tributary of the Ganga River). It flows through Madhya Pradesh and Uttar Pradesh in central India.

Thus, out of the given choices, only the Shyok River is a tributary of the Indus River.