Statement (A): In all compounds, the oxidation number of oxygen is −2 . 

Statement (B): Carbon exhibits +4 and −4 oxidation numbers only. 

Statement (C): In all compounds, the oxidation number of fluorine is −1.

Statement A is incorrect because oxygen generally exhibits an oxidation state is −2 in Oxides, But Peroxides -1, Super Oxides=$-\frac{1}{2}$, Ozonide's=$-\frac{1}{3}$

Statement B is incorrect because Carbon exhibits oxidation states from −4 to +4 and O inorganic compounds. 

Fluorine exhibits only −1 oxidation state in all compounds whereas other halogens exhibit positive oxidation state.