The correct option is D Kary Mullis
PCR or polymerase chain reaction is a technique used in molecular biology to create several copies of a certain DNA segment.
This technique was developed in 1985 by Kary Mullis, an American biochemist.
PCR has made it possible to generate billions of copies of a small segment of DNA.
James Watson and Francis Crick worked together on studying the structure of DNA and revealed the double helix structure of DNA based on the X-ray diffraction pattern by Rosalind Franklin.
Har Gobind Khorana developed a chemical method for synthesizing RNA molecules with defined sequences or combinations of bases (homopolymers and heteropolymers).
Har Gobind Khorana along with Marshall Nirenberg established the complete genetic code.