The correct option is D A−C2H6,B−CH3Cl
The reaction in which atoms combine with unsaturated carbon compounds to form saturated carbon compounds is called addition reaction. It occurs in the presence of nickel catalyst. When ethene reacts with hydrogen in the presence of a nickel catalyst then the double bond will break and hydrogen will get added at both carbons forming ethane.
During substitution reaction, the chlorine atom will replace one hydrogen atom at a time. Methane on reaction with chlorine in the presence of sunlight will give Methyl chloride and HCl.
Therefore, A is C2H6 and B is CH3Cl