In his transformation experiments, what did Griffith observe when he injected mice with a mixture of heat-killed virulent (S) bacteria and live non-virulent (R) bacteria?

In his work with pneumonia-causing bacteria and mice, Griffith found that

a. The protein coat from pathogenic cells was able to transform nonpathogenic cells.

b. Heat-killed pathogenic cells caused pneumonia.

c. Some substance from pathogenic cells was transferred to nonpathogenic cells, making them pathogenic.

d. The polysaccharide coat of bacteria caused pneumonia.

The bacteria that Griffith experimented with were termed "R" and "S" bacteria because:

In his transformation experiments, what phenomenon did Griffith observe?