Which steps are involved in the free-radical mechanism of the bromination of ethane in the presence of ultraviolet radiation?

I.     \({{\text{C}}_2}{{\text{H}}_6} + {\text{Br}} \bullet  \to {{\text{C}}_2}{{\text{H}}_5} \bullet  + {\text{HBr}}\)

II.     \({{\text{C}}_2}{{\text{H}}_5} \bullet {\text{B}}{{\text{r}}_2} \to {{\text{C}}_2}{{\text{H}}_5}{\text{Br}} + {\text{Br}} \bullet \)

III.     \({{\text{C}}_2}{{\text{H}}_5} \bullet  + {\text{Br}} \bullet  \to {{\text{C}}_2}{{\text{H}}_5}{\text{Br}}\)

A.     I and II only

B.     I and III only

C.     II and III only

D.     I, II and III

D