A student investigated the antimicrobial effectiveness of different concentrations of a newly synthesized antibiotic, Cephalexin, on the growth of Streptococcus pneumoniae.
They prepared three separate agar plates, each inoculated with a uniform lawn of Streptococcus pneumoniae bacteria. They placed a paper disc soaked in a different concentration of Cephalexin at the center of each plate. The plates were then incubated at 30 ∘C30\space^{\circ}\text{C}30 ∘C for 24 hours.
The concentrations of Cephalexin used were 0.05 mg/cm3, 0.25 mg/cm3, and 1.00 mg/cm3.
The results are shown in the diagram below:
Explain which agar plate (Plate A, Plate B, or Plate C) contains the paper disc soaked in the 0.05 mg/cm3 Cephalexin solution.
