For a line showing the relation between water content and dry density for a constant degree of saturation is __________

• A. ( _d= frac{G}{1+wG}S )
• B. ( _d= frac{G _w}{wG}S )
• C. ( _d= frac{ _w S}{1+wG} )
• D. ( _d= frac{G _w}{1+ frac{wG}{S}} )