Which statement concerning plasmids is true
Plasmids are small, circular, supercoiled DNA mole­cules found in some bacteria. They usually do not carry essential genes, but some plasmids, such as R (resistance) plasmids, carry genes coding for antibiotic resistance. All plasmids have their own origin of repli­cation, so that they are replicated along with the host chromosome and passed along to progeny cells. Only some plasmids possess genes that allow for their trans­mittal to other bacteria by the process of conjugation.