Suppose you inoculate 50 cells of an unknown single type of bacteria onto phenyl ethyl alcohol (PEA) agar. Following 24 hours of incubation, no colonies are observed on the plate. Which of the following statements is therefore accurate?

• A. The inoculated bacteria are gram-positive.
• B. The inoculated bacteria are gram-negative
• C. The inoculated bacteria are genetically modified.
• D. The culture was contaminated.

Answer: (B)