Final answer:
The thermal protection in Archaea relates to their unique membrane composition which includes ether-linked lipids and a higher ratio of saturated lipids, aiding in their survival under extreme temperatures.
Step-by-step explanation:
The question you've asked relates to how Archaea, which are a group of microorganisms, survive in extreme temperatures and what adaptations they have for thermal protection. The correct answer is b) Membrane composition. Archaeal cell membranes have a unique composition that helps them withstand extreme temperatures; they differ from bacteria and eukaryotes by having ether bonds rather than ester bonds in their membrane lipids and by typically having more saturated lipids to limit membrane fluidity. Furthermore, Archaea may possess additional adaptations like a higher proportion of guanine-cytosine in their DNA, which creates stronger hydrogen bonds and contributes to thermal stability. Extremophiles, a term applied to organisms thriving under extreme conditions, may exhibit these characteristics, and their enzymes, such as Taq polymerase from thermophilic (heat-loving) Archaea, are useful in biotechnology applications like PCR.
\