How do anthrax and tetanus bacilli withstand long periods of famine, dryness, and unsuitable temperatures?

The correct approach for how anthrax and tetanus bacilli survive harsh environmental conditions is by entering a dormant state. This dormancy allows these bacteria to withstand long periods of famine, dryness, and unsuitable temperatures by significantly reducing their metabolic activities, effectively putting them in a hibernation-like state.

During this dormant phase, the bacteria can survive for extended periods until conditions become favorable for growth and reproduction. When the environment becomes more suitable (such as the presence of nutrients and adequate moisture), these bacilli can reactivate and begin to multiply, leading to infections in hosts.

The option regarding a waxy outer shell may suggest a protective mechanism, but it is not the primary reason these specific bacteria can endure extreme conditions for long periods. Rapid reproduction and increased metabolic activity would be counterproductive strategies in the face of famine and adverse environmental conditions, as these actions would require resources that are not available during such times. Thus, the capacity to enter a dormant state is what enables these bacilli to survive until conditions improve.