Which two of the following statements are correct regarding the influence of population composition on the effectiveness of an antimicrobial agent?
A) Population composition has no impact on the effectiveness of an antimicrobial agent.
B) Population composition can affect the effectiveness of an antimicrobial agent due to variations in susceptibility among different groups.
C) Population composition primarily influences the dosage required for an antimicrobial agent to be effective.
D) Population composition only affects the effectiveness of antimicrobial agents in certain geographical regions.