The biological concept of species was proposed by ........

Three different genera $Solanum$,$Petunia$,and $Datura$ are placed in the family:

The suffix used for denoting a sub-family in biological classification is .........

The taxonomic category that consists of organisms with maximum similarity and the ability to interbreed to produce fertile offspring is .........

$A.$ Maize is included in the class Monocotyledonae.
$R.$ This class does not contain any order.

What is a species?