The tetrahalide shown is heated with $\mathrm{SbF}{}_3$ in the presence of a little $\mathrm{SbCl}{}_5$ (Swarts reaction) until exactly two halogen atoms have been exchanged. Which structure is the product?

The Swarts reaction exchanges chlorine for fluorine using a metallic fluoride such as SbF3. Replacing two of the four chlorines in carbon tetrachloride gives dichlorodifluoromethane, CCl2F2 (Freon-12). The trifluoro and tetrafluoro compounds correspond to three and four exchanges and the monofluoro compound to one.