George W. Beadle and Edward L. Tatum showed that genes direct the synthesis of enzymes that control metabolic processes. From Beadle and Tatum's work arose a basic hypothesis "One gene specifies the production of one enzyme".
Har Gobind Khorana was an Indian-American biochemist renowned for his research on the role of nucleotides in protein synthesis for which he won the Nobel Prize.
Avery and his coworkers found that DNA was the mechanism for the transfer of genetic information between the two bacteria.
Joshua Lederberg won a noble prize for his discovery of conjugation. He also discovered transduction in bacteria.
Thus, the correct answer is option B.