The correct option is C its ability to carry a foreign gene
Plasmids are extra-chromosomal, self replicating, usually circular, double stranded DNA molecules found naturally in many bacteria and also in some yeasts. Plasmids are usually not essential for normal cell growth and division, but they often confer some traits to the host organism e.g., resistance to certain antibiotics. The plasmid that is used as a carrier for transferring a fragment of foreign DNA into a suitable host is called the vehicle DNA or the cloning vector or the gene carrier.