Consider the following statements and choose the correct answer:
In order to be a useful vector, a plasmid:
1. Must possess the genes essential for replication of DNA
2. Must carry, at least, one gene that can be used as a marker for the selection of the plasmid in the transformed cell
3. Must include, at least, one gene recognizable by its product or activity, which possesses within it a cutting site for a restriction enzyme
4. In the rep region must contain a cutting site for the restriction enzyme to be used