Allyl amine is an organic compound with the formula \( CH_2=CH-CH_2NH_2 \). It consists of a propene (propylene) backbone with an amino group (-NH2) attached to the second carbon.
The IUPAC name for this compound is "2-aminopropene," as the amino group is attached to the second carbon of the propene chain.
Thus, the correct answer is \( B \).