Step 1: Known antiseptics
Dettol (chloroxylenol and terpineol), tincture of iodine, boric acid, and thymol are common antiseptics.
Step 2: Eliminate
The other three are chemotherapeutic drugs used inside the body.
Step 3: Conclusion
Thymol is the answer.
Final Answer:
Thymol is the antiseptic.
\[ \boxed{\text{(B) }\text{Thymol}} \]