Griffith demonstrated transformation with -: (A) H. influenzae, (B) E. coli, (C) Proteus, (D) Pneumococcus
Answer is D. Griffith in 1928 found that mice died when injected with a mixture of live non-capsulated (R) pneumococci and heat killed capsulated (S) pneumococci, neither of which separately proved fatal. REF:Ananthanarayan and Panicker's Textbook ofMicrobiology 8thEdition pg no:63