Which of the following equations as suggested by Colebrook and White gives the increase in roughness of a new surface (ε0) with age/time (t) (where, ε = roughness of the surface after time’t’. α = a co-efficient to be experimentally determined) ?

• A. ε = ε0 + α.t
• B. ε = ε0 + α.t2
• C. ε = ε0 + α.t3
• D. ε = ε0 + α.t4