Final answer:
The most stress-resistant form of life is endospores, with biofilms being another hard-to-eliminate form. Endospores can withstand extreme conditions, while biofilms protect microorganisms through a sticky matrix that resists antibiotics and sterilization.
Step-by-step explanation:
The most stress-resistant form of life are endospores. Endospores are dormant, tough, and non-reproductive structures produced by certain bacteria from the genera Bacillus, Clostridium, and others. They are formed in response to adverse environmental conditions and can survive extreme heat, lack of water, exposure to chemicals, and even radiation. Bacteria can remain in this dormant state for very long periods until favorable conditions return, making them very hard to eliminate.
Another form of stress-resistant life is biofilms. Biofilms are communities of microorganisms that are enmeshed in a self-produced matrix of extracellular polymeric substance (EPS) which makes them resistant to antibiotics and disinfectants. This protective environment allows the bacteria within biofilms to withstand various types of stress more effectively than their planktonic, or free-living, counterparts.
In conclusion, option A) Endospores; Biofilms is the correct answer as both endospores and biofilms are extremely resilient and difficult to destroy, having developed specialized adaptations to survive harsh conditions.