If weight of rammer is W, free fall height is h, number of layers is N, number of blows is n, acceleration due to gravity is g and volume as V, then the formula for energy per volume is ______

• A. \(\frac{WhNng}{V} \)
• B. \(\frac{WVNng}{h} \)
• C. \(\frac{Whng}{N} \)
• D. \(\frac{WgN}{hnV} \)