Explanation:

- The Indus Waters Treaty is a water-distribution agreement between India and Pakistan.

- It was signed to resolve disputes over water sharing of the Indus River system.

Option:1, 19 September 1960

- This is the correct date when the Indus Waters Treaty was signed.

Option:2, 12 November 1959

- This date is not related to the signing of the Indus Waters Treaty.

Option:3, 16 December 1963

- This date does not pertain to the treaty or relevant events regarding it.

Option:4, 18 October 1969

- This is unrelated to the treaty, which had already been signed in 1960.