The process for removing layers of basic oxides from metal before electroplating is called:

The correct option is C pickling
$\begin{array}{c}\text{Pickling is the removal of basic oxide layers from}\\ \text{metal befor electroplating.}\\ \text{Pickling is done by dipping the impure metal in dil. acid}\\ \text{so as to remore the basic layer on it.}\\ \text{so, option (C) is correct.}\end{array}$