Who was responsible for constructing the first recombinant DNA?

The correct answer is Option (4) → Both (1) and (2)

The first recombinant DNA was made in 1972 by Stanley Cohen and Herbert Boyer. They cut out a piece of DNA carrying an antibiotic resistance gene from a plasmid and linked it with a native plasmid of Salmonella typhimurium.

Option (1) Stanley Cohen — Correct statement, but Cohen was one of the two scientists, so on his own he is not the answer.

Option (2) Herbert Boyer — Correct statement, but Boyer worked together with Cohen, so on his own he is not the answer.

Option (3) Temin and Baltimore — Incorrect. Temin and Baltimore are not connected with the construction of the first recombinant DNA in the book.

NCERT Extract:
Principles of Biotechnology – “… Let us now focus on the first instance of the construction of an artificial recombinant DNA molecule. The construction of the first recombinant DNA emerged from the possibility of linking a gene encoding antibiotic resistance with a native plasmid (autonomously replicating circular extra-chromosomal DNA) of Salmonella typhimurium. Stanley Cohen and Herbert Boyer accomplished this in 1972 by isolating the antibiotic resistance gene by cutting out a piece of DNA from a plasmid which was responsible for conferring antibiotic resistance.”