Which of the Following Are Elementary Reactions? Select All That $\rightarrow$

Which of the following are elementary reactions? Select all that apply.

A) H ^. +Cl₂ $\rightarrow$ HCl + Cl ^.
B) 2 NO (g) + O₂ (g) $\rightarrow$ 2NO₂ (g)
C) BrO₃^- (aq) + 5Br^- (aq) + 6H₃O⁺ (aq) $\rightarrow$ 3Br₂ (aq) + 9H₂O (aq)
D) (CH₃) ₃C⁺ + H₂O $\rightarrow$ [(CH₃) ₃COH₂]⁺