This option is repeated from option A. It suggests that vinyl alcohol and acetaldehyde are position isomers. However, this is not an accurate description of their relationship.
Vinyl alcohol and acetaldehyde are not functional group isomers of each other.
Metamers are a type of structural isomerism where molecules have the same molecular formula but differ in the connectivity of their atoms. Vinyl alcohol and acetaldehyde do have the same molecular formula (C2H4O) but differ in the arrangement of atoms, making them metamers.
Tautomers are a type of structural isomerism where molecules exist in equilibrium between two different structural forms that can rapidly interconvert. Vinyl alcohol and acetaldehyde are tautomers of each other. In other words, they can transform into each other by the movement of a hydrogen atom and a double bond.
The correct description for the relationship between vinyl alcohol and acetaldehyde is D. Tautomers. They are tautomeric forms of each other, which means they can rapidly interconvert.