A bromine atom abstracts one hydrogen atom from the compound shown. Which radical shown is the most stable one that can form?

The compound shown is 3-phenylbut-1-ene. The C3-H is simultaneously allylic and benzylic, and the radical formed there is also tertiary, so the unpaired electron is delocalised over the vinyl group and the benzene ring. The primary radical, the aryl radical and the vinylic radical lack both resonance and substitution, so the C3 radical is the most stable.