Gem- dibromide is

The main difference between geminal dihalide and vicinal dihalides is that geminal dihalides have both halide groups attached to the same carbon atom of the compound whereas vicinal dihalides have two halide groups which are attached to two adjacent carbon atoms in the same compound.

In the given options, only option-B is geminal dihalide where second carbon has two Br atoms.

Among the given options, option-B is correct.