In Sia and Dawson's 1931 Experiment

In Sia and Dawson's 1931 experiment:

A) Mice were required to demonstrate the transforming principle
B) Used serum to precipitate IIIS cells from a mixture of heat-killed IIIS and living IIR cells
C) They showed that mice play no direct role in the transforming principle
D) Heat-killed IIR cells mixed with living IIIS cells gave rise to IIR colonies
E) None of these