Explanation:

- Indus River:

- Originates in Tibet near Lake Manasarovar.

- The longest river in Pakistan.

- Flows through several regions, including India and Pakistan.

- ?? Correct Answer: Option 2 - Indus.

- Chenab River:

- Begins in the Himalayas in India.

- It's a major river in Pakistan but does not originate from Lake Manasarovar.

- Sutlej River:

- Also originates near Lake Manasarovar in Tibet.

- While significant, it is not the longest in Pakistan.

- Kabul River:

- Originates in Afghanistan.

- It is a crucial river for both Afghanistan and Pakistan but is not associated with Lake Manasarovar.