Final answer:
The unique feature to archaea among the given options is hami (D), which are attachment structures that resemble grappling hooks, specific to archaeal cells.
Step-by-step explanation:
The unique feature to archaea among the options provided is D) hami. These are unique grappling hook-like structures found on the surface of some archaeal cells and serve as a means of attachment, somewhat analogous to bacterial fimbriae. However, they are structurally distinct and specific to archaea. In contrast, peptidoglycan is found in bacterial cell walls, while fimbriae and pili are known to be utilized by both bacteria and archaea for attachment and genetic exchange, respectively. LPS (lipopolysaccharide) is a component found in the outer membrane of gram-negative bacteria, not archaea.