Q. 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 0.38, 0.79 and 0.22 respectively. The screen effectiveness based on the oversize is

• (A) 0.5
• (B) 0.58
• (C) 0.68
• (D) 0.62