A sand mixture was screened through a standard $10-$mesh screen. The mass fraction of the oversize material in feed, overflow and underflow were found to be $0\mathrm{.}38,0\mathrm{.}79$ and $0\mathrm{.}22$ respectively. The screen effectiveness based on the oversize is

$0\mathrm{.}5$

$0\mathrm{.}58$

$0\mathrm{.}68$

$0\mathrm{.}62$