The operation involved when the soluble material is largely on the surface of an insoluble solid and is merely washed off by the solvent is called__________________?

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The operation involved when the soluble material is largely on the surface of an insoluble solid and is merely washed off by the solvent is called__________________?

A. Decoction
B. Percolation
C. Elutriation or elution
D. None of these