Olefins can be hydrogenated by
Raney Ni and H2
Lindlar's Catalyst and H2
Pt and H2
Zn-HCl involves proton transfer to the substrate.
The other three a, b, c & d are all well known catalysts for hydrogenation
A hydrocarbon of unknown structure has the formula C8H10. On catalytic hydrogenation over the Lindlar catalyst, 1 equivalent of H2 is absorbed. On hydrogenation over a palladium catalyst, 3 equivalents of H2 are absorbed. Suggest several structures: