The correct option is C Halogen exchange
The Finkelstein reaction is an organic reaction where an alkyl halide is converted into another alkyl halide by reacting with NaI. Here exchange of halogen take place. This reaction is called Finkelstein Reaction.
C2H5BrEthyl Bromide+NaIDry Acetone−−−−−−−→HeatC2H5IEthyl Iodide+NaBr↓