The term species was coined by

$A :$ Species is a genetically closed system.
$R :$ Because the reproductive isolation constitutes the most important boundary between different species.

Genus is a group of similar and related

As we go from species to kingdom in a taxonomic hierarchy,the number of common characteristics

Assertion $A$: Linnaeus is known as the father of taxonomy.
Reason $R$: Linnaeus classified plants into $24$ groups based on floral characteristics.
Which option is correct for Assertion $A$ and Reason $R$?

$A$ species can be considered as . . . . . . .