Assume Clostridium perfringens in cooked beef doubles every 20 minutes when held in the danger zone. If a pot of beef contains 1,000 vegetative cells immediately after cooking, estimate how long (in hours and minutes) it would take to reach 100,000,000 cells (1×10^8) under continuous danger zone conditions. Show your calculation.

• A. Approximately 2 hours and 45 minutes because 1,000 cells reach dangerous levels after a few hours of doubling at 20-min intervals.
• B. Approximately 5 hours and 32 minutes (≈5.5 hours).
• C. Around 12 hours, as bacteria require many more cycles than doubling every 20 minutes to reach very high counts from a low starting point.
• D. Less than 1 hour because exponential growth is extremely rapid and will reach 1×10^8 in under 60 minutes at a 20-minute doubling rate.

Answer: (B)