Final answer:
The SO3H group in the sulfonation of benzene with an isopropyl group and bromine will attach at the ortho position relative to the isopropyl group, which is option b) Position 2.
Step-by-step explanation:
In a sulfonation reaction of a benzene ring that contains an isopropyl group with bromine, the SO3H group will attach to the ring in a position that is dictated by the existing substituents' directing effects. The isopropyl group is an activating and ortho/para-directing group.
Since the bromination has already occurred and assuming it took place at the para position relative to isopropyl (as the student's question implies bromine at the fourth position), the sulfonation will occur at the ortho or para position relative to the isopropyl group. Given the options a), b), c), d), the correct answer would be position 2, which is the ortho position relative to the isopropyl group.