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When an alkene undergoes hydrogenation, the process involves the addition of hydrogen (H₂) across the carbon-carbon double bond of the alkene, resulting in the formation of an alkane. The hydrogenation reaction typically occurs in the presence of a catalyst, such as platinum, palladium, or nickel, which facilitates the breaking of the double bond and allows hydrogen atoms to bond to the carbon atoms.

In this reaction, the unsaturated alkene, characterized by its double bond, becomes saturated as the newly added hydrogen atoms occupy the former double bond locations. Thus, the product is a saturated hydrocarbon with single bonds only — the alkane.

On the other hand, other options like alkoxide, alkyne, or alcohol do not emerge from a straightforward hydrogenation reaction of alkenes. Alkoxides are typically formed from the reaction of alcohols with strong bases, alkynes are unsaturated hydrocarbons with carbon-carbon triple bonds, and alcohols result from hydration reactions, not from hydrogenation of alkenes. Therefore, the formation of an alkane is a direct result of hydrogenation.