(N/A) The classification systems have undergone several changes over time.
$1$. The first scientific attempt at classification was made by Aristotle,who classified plants into herbs,shrubs,and trees,and animals based on the presence or absence of red blood cells.
$2$. This system was limited and could not classify all known organisms.
$3$. Linnaeus later proposed a two-kingdom system consisting of Plantae and Animalia. However,this system failed to distinguish between unicellular and multicellular organisms,and between prokaryotes and eukaryotes.
$4$. To address these limitations,$R.H. Whittaker$ proposed the five-kingdom system of classification in $1969$. This system classifies organisms into Monera,Protista,Fungi,Plantae,and Animalia based on criteria such as cell structure,body organization,mode of nutrition,and phylogenetic relationships.