The mechanism that causes a gene to move from one linkage group to another is called
(3) Translocation is the process causing a gene to move from one linkage group to another. It is the separation of a chromosome segment and its union to a non-homologous chromosome. It is of two types - Simple and reciprocal.
In simple translocation one chromosome shows deletion of deficiency while a non-homologous chromosome comes to have an additional segment. In reciprocal translocation two non-homologous chromosomes exchange segments between themselves to create new linkage groups in both the chromosomes.
Hence, option (3) is correct.