The Assam movement from 1979 to 1985 was against-

Illegal Bengali Muslim settlers from Bangladesh in Assam.

The correct answer is Option (3) → Illegal Bengali Muslim settlers from Bangladesh in Assam.

"The Assam Movement from 1979 to 1985 is the best example of such movements against ‘outsiders’. The Assamese suspected that there were huge numbers of illegal Bengali Muslim settlers from Bangladesh. They felt that unless these foreign nationals are detected and deported they would reduce the indigenous Assamese into a minority. There were other economic issues too. There was widespread poverty and unemployment in Assam despite the existence of natural resources like oil, tea and coal. It was felt that these were drained out of the State without any commensurate benefit to the people.  ".