The correct option is A Descending of carbon atoms
All the three reactions show similarity in descending of carbon atoms.
The number of carbon atoms in the product is lees than the number of carbon atoms in the reactant.
(a)CH3CONH2+Br2+4KOH⟶XH3NH2+K2CO3+2Kr+2H2O Hoffmann's bromamide reaction.
(b)CH3COOH+sodalime⟶CH4+CO2 Decarboxylation.
(c)CH3COOAg+Br2⟶CH3Br+CO2+AgBr