单项选择题
9. Quorum sensing (QS)
a. is a unique characteristics of biofilm.
b. provides communication among bacteria via molecules released into the environment.
c. regulates gene expression including virulence gene expression.
d. all the above.
A．a. is a unique characteristics of biofilm.
B．b. provides communication among bacteria via molecules released into the environment.
C．c. regulates gene expression including virulence gene expression.
D．d. all the above.
