Step 1: Concept
Disinfectants are chemical substances used to kill or inhibit the growth of microorganisms. Dettol is a well-known brand of antiseptic liquid widely used for disinfection purposes.
Step 2: Meaning
The main constituent refers to the primary active ingredient responsible for the disinfectant's effectiveness in killing bacteria and other microorganisms.
Step 3: Analysis
Option A: Chloroxylenol and terpineol are indeed the main constituents of Dettol. Chloroxylenol is a phenolic compound that acts as an antiseptic, while terpineol is a terpene alcohol used for its pleasant smell.
Option B: Bithionol is not commonly associated with Dettol; it is more related to other disinfectants or pesticides.
Option C: Iodine is used in some antiseptics but is not the primary constituent of Dettol.
Option D: Phenol, while a common ingredient in many antiseptics, is not the main constituent of Dettol.
Step 4: Conclusion
The primary active ingredients in Dettol are Chloroxylenol and terpineol.
Final Answer: (A)