The primary carbocation shown undergoes a 1,2-phenyl shift (through a bridged phenonium ion). Which structure shown is the cation formed?

The cation shown is the neophyl cation. The phenyl group migrates from the quaternary carbon to the CH${}_2^{+}$ carbon, so the charge moves to the carbon that carried the phenyl group and now bears two methyl groups and a benzyl group. The product is the 2-methyl-1-phenylpropan-2-yl cation; the methyl-shift product would need migration of a methyl group, not phenyl.