In the five-kingdom system,the main basis of classification is

$A$: Unicellular eukaryotes are included in Monera.
$R$: Unicellular eukaryotes have $70S$ cytoribosomes.

The system of classification based on evolutionary and genetic relationships among organisms,ignoring the morphological similarities or differences,is called

Engler and Prantl published a phylogenetic system in the monograph:

$A$: Biodiversity of the prokaryotes cannot be estimated.
$R$: Conventional taxonomic methods are not suitable for identification and characterisation of microbes.

Which of the following domains lacks a cell wall?