Which of the following are used in gene cloning?

A cloning vector is a small piece of DNA, taken from a virus, a plasmid, or the cell of a higher organism, that can be stably maintained in an organism, and into which a foreign DNA fragment can be inserted for cloning purposes. The plasmids most commonly used in recombinant DNA technology replicate in E. coli. Most plasmid vectors contain a drug-resistance gene or genes that confers additional survival properties to the bacteria. The DNA to be cloned replaces any one of these genes. So, the correct answer is 'Plasmids'