Answer: 1,2 and 3.
The following are common to transformation, transduction and conjugation.
1. Unidirectional transfer of genes.
2. Incomplete gene transfer.
3. Homologous recombination.
Step-by-step explanation:
Transformation is the taking up of free DNA from the environment.
Transduction is the transfer of DNA by bacteria to a viruses.
Conjugation is the transfer of Plasmid or circular DNA through a tube between the cells. Incomplete DNA are transferred unidirectional .