Concept:In IUPAC nomenclature, the principal functional group gets the lowest possible number.
Explanation:The compound contains an amine group,
−NH2​, and a double bond.
The amine group is the principal functional group, so it has higher priority than the double bond while numbering the chain.
The longest carbon chain that includes both the
−NH2​ group and the double bond has five carbon atoms, so the parent name is pentene.
Number the chain from the end nearer to the amine group.
This gives the amine group the locant 2 and the double bond the locant 3.
Numbering from the opposite end would place the amine group at carbon 4, which is not allowed because the principal functional group must receive the lowest locant.
Therefore, the correct IUPAC name is Pent-3-en-2-amine.
Answer:B. Pent-3-en-2-amine
