Final answer:
Genes are indicated to be linked through the process of recombination, which occurs during sexual reproduction or via horizontal gene transfer mechanisms like conjugation, transformation, or transduction.
Step-by-step explanation:
The indication that genes are linked is given by recombination. Recombination refers to the process where genetic material is rearranged during sexual reproduction or through mechanisms of horizontal gene transfer in bacteria, such as conjugation, transformation, and transduction. Conjugation is particularly mentioned as a mechanism by which genes for antibiotic resistance can be transferred between bacteria, contributing to the spread of resistance within a population.