Frederick Griffith heat-killed a culture of pathogenic bacteria. He split the sample and injected half of it into mice. The mice lived. He then mixed the other half with a living, nonpathogenic bacteria strain and injected the mixture into mice. The mice died. These results best support which of the following conclusions. a. a substance had been transferred from pathogenic to nonpathogenic bacteria
b. the initial heat treatment was unsuccessful
c. splitting the culture revived the pathogenic bacteria
d. non-pathogenic bacteria were transformed by pathogenic capsule proteins