Hydrogenation: Hydrogenation is the addition of hydrogen (H2) to a molecule, typically in the presence of a metal catalyst (like Pt, Pd, or Ni). It's commonly used to reduce multiple bonds (alkenes and alkynes) to single bonds (alkanes).
Catalytic Hydrogenation and Stereochemistry: In catalytic hydrogenation with a metal catalyst, hydrogen adds to the *same face* of the double bond (syn addition). This is because both hydrogen atoms are adsorbed onto the surface of the metal catalyst, and the alkene approaches the catalyst surface from one side.
Analyzing the Reactant and Products: The reactant contains a double bond in a cyclic system. Option 3 shows the addition of two hydrogen atoms on the *same side* of the ring (syn addition). Therefore, only **Option 3** corresponds to this stereochemical outcome. Other products show anti addition that doesn't match the process.
Therefore, the product of the hydrogenation reaction is the isomer in which both hydrogen atoms have been added to the *same face* of the original double bond, corresponding to the structure in Option 3.
