Which one of the following alkenes will react faster with H2 under catalytic hydrogenation conditions ?
(R = Alkyl substituent)

The rate of hydrogenation of an alkene under catalytic conditions depends on the stability of the intermediate formed during the reaction. More substituted alkenes form more stable intermediates and thus react faster. Among the given options, the alkene with the most alkyl substituents (which would be the most substituted) would react the fastest. Typically, the order of reactivity is: tetrasubstituted > trisubstituted > disubstituted > monosubstituted > unsubstituted. Without the specific structures, we can infer that the correct answer is the one that represents the most substituted alkene.