The methods NOT involved in concentration of ore are (A) Liquation...

Electrolysis is not a concentration method. Electrolytic refining is a process of refining a metal (mainly copper) by the process of electrolysis.

Liquation is not a concentration method. It is a refining method. In this method a low melting metal like tin can be made to flow on a sloping surface. In this way it is separated from higher melting impurities.

The other three methods are concentration methods of ores.

Leaching is used when the ore is soluble in a solvent. The powdered ore is dissolved in a chemical, usually a strong solution of $NaOH$. The chemical solution dissolves the metal in the ore, and it can be extracted and separated from the gangue by extracting the chemical solution.

Froth flotation is a process for selectively separating hydrophobic materials from hydrophilic.

Hydraulic washing is a technique used when the impurities are lighter and the ore particles are heavier. The lighter impurities are removed by washing in current of water. As gold particles are heavier than the impurities like sand, we can use hydraulic washing for the concentration of ores of gold.