In the silver plating of copper, $K[Ag(CN)_2]$ is used instead of $AgNO_3$. The reason is : -

Question

( A ) A thin layer of Ag is formed on Cu
( B ) Less availability of $Ag^+$ ions, as Cu can not displace Ag from $[Ag(CN)_2 ]^- ion$
( C ) More voltage is required
( D ) $Ag ^+$ ions are completely removed from solution