I can only see the list of possible reactants in the image:
Lead nitrate, Copper, Hydrochloric acid, Lead oxide, Iron, Sodium carbonate, Copper carbonate, Chlorine
But the actual reaction scheme containing A, B and C is not visible in the uploaded image, so I cannot identify A, B and C correctly from this image alone.
Please upload the full reaction scheme image, and then I will give you the exact answer in the same detailed HTML format.