Question

the sequencing of rrna allowed scientists a clear understanding that all dna is relatively the same across domains. that archaea are more similar to bacteria than to eukaryotes. that half of the sequences of archaea were previously unknown. of the unambiguous relationships among different prokaryotic species. that certain nucleic acid sequences are unique to archaea and eukaryotes.

Explanation:

rRNA sequencing has shown that certain nucleic - acid sequences are unique to archaea and eukaryotes. DNA varies across domains. Archaea are more similar to eukaryotes in some aspects than to bacteria. There is no evidence for half of archaea sequences being previously unknown from rRNA sequencing, and relationships among prokaryotic species are complex and not always unambiguous.

Answer:

that certain nucleic acid sequences are unique to archaea and eukaryotes.