When purified virulent pneumococci DNA was introduced to avirulent pneumococci, Avery and his colleagues observed . Multiple choice question. no death in test animals only growth of avirulent pneumococci, indicating DNA was NOT the agent of transformation death of test mice growth of virulent pneumococci, indicating DNA was the agent of transformation

death of test mice, growth of virulent pneumococci, indicating DNA was the agent of transformation

Explanation:

In an experiment conducted by three scientists namely: Oswald Avery, Colin MacLeod and Maclyn McCarty in 1944, it was proven that DNA is the substance that causes transformation in bacteria as opposed to proteins.

In this experiment, Avery and his colleagues combined a dead but virulent strain of Streptococcus pneumoniae & a living but avirulent strain of the same bacterium and inserted into a living rat. They found out that the test specimen (rat) died and observed the growth of the virulent pneumococci.

This suggests that the virulent strain of bacteria has transferred its virulent DNA via transformation into the avirulent strain to kill the rat. Hence, indicating DNA as the agent of transformation.