Transformation is the transfer of genetic material from one bacterial strain to other without establishing a physical contact. Griffith proved that transforming principle is involved by his transformation experiment on virulent (SIII) and non-virulent strains (RII) of Diplococcus pneumonia. Option A is correct. Transformation experiment does not establish any link between the parallel behaviour of DNA and chromosomes; option C is incorrect. Lederberg and Tatum demonstrated that a nutritional strain of E. coli, when grown with normal strain, was transformed into the normal strain that can grow on the minimal medium; option B is incorrect. Hogeland and Zemenick were first to show that tRNA serve as Crick’s adaptor molecules in protein synthesis; an essential link that transfers the genetic information of mRNA into an amino acid sequence of protein. Option D is incorrect. The correct answer is A.