If D_p is the equivalent diameter of a non-spherical particle, V_p its volume and S_p its surface area, then its sphericity is Φ_s is defined by

A. Φ_s $$ = \frac{{6{{\text{V}}_{\text{p}}}}}{{{{\text{D}}_{\text{p}}}{{\text{S}}_{\text{p}}}}}$$

B. Φ_s $$ = \frac{{{{\text{V}}_{\text{p}}}}}{{{{\text{D}}_{\text{p}}}{{\text{S}}_{\text{p}}}}}$$

C. Φ_s $$ = \frac{{6{{\text{D}}_{\text{p}}}{{\text{S}}_{\text{p}}}}}{{{{\text{V}}_{\text{p}}}}}$$

D. Φ_s $$ = \frac{{{{\text{D}}_{\text{p}}}{{\text{S}}_{\text{p}}}}}{{{{\text{V}}_{\text{p}}}}}$$

Answer: Option A