Penetration theory states that the mass transfer co-coefficient is equal to (where, D_e is diffusivity and 't' is time)

A. $${\left( {{{\text{D}}_{\text{e}}}.{\text{t}}} \right)^{\frac{1}{2}}}$$

B. $${\left( {\frac{{{{\text{D}}_{\text{e}}}}}{{\text{t}}}} \right)^{\frac{1}{2}}}$$

C. $${\left( {\frac{{4{{\text{D}}_{\text{e}}}}}{{\pi {\text{t}}}}} \right)^{\frac{1}{2}}}$$

D. $$\frac{{4{{\text{D}}_{\text{e}}}}}{{\text{t}}}$$

Answer: Option C