Step 1: Concept
Electronegativity determines the oxidation state of an element in a compound.
Step 2: Analysis
- Fluorine is the most electronegative element in the periodic table.
- Unlike other halogens (Cl, Br, I), Fluorine does not have $d$-orbitals to expand its octet and cannot show positive oxidation states.
Step 3: Conclusion
Fluorine always shows an oxidation state of -1 in all its compounds.
Final Answer: (B)