Explanation:

- The Namami Gange Programme is an integrated conservation mission.

- It was approved by the Government of India for achieving effective abatement of pollution and conservation of the river Ganga.

- Option 1: 2014 – The programme was indeed launched and approved in 2014.

- Option 2: 2018 – This year is not related to the approval of the programme, though there may have been initiatives and projects started under the program during this time.

- Option 3: 2019 – Similar to 2018, this does not relate to the original approval.

- Option 4: 2015 – This was a subsequent year but not the year of approval.