A mixture of salt and sugar can be separated by the process of filtration.
To separate the given mixture we can use sieving, i.e., by using a sieve with very fine pores, we can separate salt from sugar based on their different particle size. Salt will pass through the pores because of very small size in comparison to sugar crystals which will be left behind.
Filtration is a method that is used to separate insoluble solids from a liquid. So, filtration cannot be used to separate the given mixture.