$Order$ is the assemblage of families which exhibit a few similar characters.

In which of the following systems of classification is each character given equal importance,and at the same time,hundreds of characters can be considered?

$A$ species is taxonomically defined as:

............... has a group of related genera.

How many of the following statements are correct?
$(A)$ Each taxonomic category is a unit of classification.
$(B)$ Taxonomic groups are distinct biological entities.
$(C)$ Genera are aggregates of closely related families.
$(D)$ Both vegetative and reproductive characters are used to characterise the families.

Which one of the following is a species?