Soap helps in cleaning clothes, because
Chemicals of soap change
It increases the surface tension of the solution
It absorbs the dirt
It lowers the surface tension of the solution
As we learnt in Surface tension that due to surface tension, liquids tend to minimize their surface area.
Thus, Soap helps to lower the surface tension of the solution, thus soap get stick to the dust particles and grease and these are removed by action of water.
Therefore, Option (4) is correct