Why Would Normal Flora Isolating from Immunosuppressed Patients Undergo Antimicrobial

Why would normal flora isolating from immunosuppressed patients undergo antimicrobial susceptibility testing?

A) These are not normal flora; they are other potential pathogens that have the same colonial morphology as normal flora.
B) Species usually viewed as normal flora may be responsible for an infection in an immunosuppressed patient.
C) All bacteria isolated from immunosuppressed patients must have antimicrobial susceptibility tests performed.
D) Cultures from immunosuppressed patients only grow pathogenic organisms that must undergo antimicrobial susceptibility testing.