Bleaching powder is produced by the action of chlorine on?

Correct option is B

The correct answer is (b) Slaked lime.
Explanation: Bleaching powder is produced by the action of chlorine on slaked lime (calcium hydroxide, Ca(OH)₂
The chemical reaction for the production of bleaching powder is:
​$$Ca(OH)_2+Cl_2→Ca(OCl)_2+H_2O$$​​
This reaction produces calcium oxychloride (Ca(OCl)₂), which is commonly known as bleaching powder.
Other Options: 

•  Sodium chloride: Chlorine can react with sodium chloride to form sodium chloride and chlorine gas, but it doesn't produce bleaching powder.
  
• Caustic soda: Caustic soda (sodium hydroxide) reacts with chlorine to form sodium chloride and sodium hypochlorite, but not bleaching powder.
  
•  Quick lime: Quick lime (calcium oxide) reacts with water to form slaked lime (calcium hydroxide), but it does not directly form bleaching powder.