What is the IUPAC name of the compound shown?

• A. 1-Cholor-2-fluorocyclobut-1-ene
• B. 2-Chloro-1-fluorocyclobut-1-ene
• C. 1-Chloro-2-fluorocyclobut-2-ene
• D. 1-Fluoro-2-chlorocyclobut-1-ene