Who among the following was associated with the suppression of Thugs ?

The correct answer is (2) Captain Sleeman. Captain (later Major‑General) William Henry Sleeman was the leading British officer in the campaign against Thuggee and is explicitly credited with its suppression; contemporary sources name him as the officer associated with that work. Sleeman was appointed General Superintendent and later Commissioner for the Suppression of Thuggee and Dacoity, taking office in February 1839 and directing systematic operations and investigations into the fraternity [1]. His published account and official reports documented the methods used, the role of informers, and the large number of convictions and sentences that effectively dismantled organized Thuggee networks [1].

Sources

1. [1] https://victorianweb.org/history/empire/india/thuggee.html
2. [2] https://en.wikipedia.org/wiki/William_Henry_Sleeman