The correct option is C Gene cloning
Gene cloning is a method where a gene is introduced into a self replicating vector and made to grow continuously to obtain several million copies of the gene of interest. This is useful to preserve the gene of interest in a lab. Although PCR is also a step involved in making multiple copies of DNA, it doesnot necessarily involve the amplification or obtainment of mutliple copies of gene. Gene amplification is mostly done through gene cloning.