Options for the question have not been provided. They are as follows:
A destroying type SIII DNA with DNase
B destroying type SIII RNA with RNase
C the control group, in which all components are intact
D destroying type SIII lipids and polysaccharides
E destroying type SIII proteins with protease
Answer:
A destroying type SIII DNA with DNase
Explanation:
Griffith proved that a "transforming principle" was responsible for transforming the non virulent RII bacteria into the virulent SIII bacteria. When heat killed SIII and living RII were injected together into the mice, they still died because the transforming principle had entered from SIII strain to RII strain and also transformed it into SIII.
Avery, Macleod and McCarty carried further the work of Griffith to determine the chemical nature of the transforming principle. Many people thought that it was protein. But when they destroyed the SIII protein with protease, the transformation still occurred killing the mice.
Transformation only did not occur in the case where they destroyed SIII DNA by DNase. When this mixture was injected into the mice, the mice still lived which proved that DNA is an essential component of transforming principle and without taking it up, non virulent strain can not become virulent.
