Final answer:
The compound with the structure -(benzene circle)-CH2CH=CH2 is correctly named as 3-phenyl-1-butene.
Step-by-step explanation:
The correct name for the structure -(benzene circle)-CH2CH=CH2 involves identifying the benzene ring with a substituent. Here, the benzene ring is attached to a longer carbon chain, which makes the benzene ring a phenyl group. The longest carbon chain attached to the phenyl group has four carbon atoms, which is butane, and the presence of a double bond at the second and third carbon atoms makes this compound an alkene. Hence, this compound is named after the longest carbon chain with the highest priority functional group, which is the alkene, followed by the position of the phenyl group. Therefore, the complete name of the compound is 3-phenyl-1-butene.