In Griffith's Experiment, Why Were S-Type Cells Virulent and R-Type

Multiple Choice

In Griffith's experiment, why were S-type cells virulent and R-type cells not virulent?

A) S-type cells contain the transforming substance, and R-type cells do not.
B) S-type cells have DNA, and R-type cells do not.
C) S-type cells have a protective smooth capsule, and R-type cells do not.
D) S-type cells could not be killed by heat treatment, and R-type cells could.
E) S-type cells were resistant to DNase treatment, and R-type cells were not.