Option A: Cetyltrimethylammonium bromide → This is a cationic detergent (a quaternary ammonium compound). Thus, it is a synthetic detergent. Option B: Sodium stearate → This is the sodium salt of a fatty acid (stearic acid) - it is a soap, not a synthetic detergent. Option C: Sodium laurylsulphate → This is an anionic synthetic detergent (commonly called SDS or SLS). Option D: Sodium dodecylbenzenesulphonate → This is also an anionic synthetic detergent, one of the most commonly used (found in many household detergents).
