Fill in the blanks $A$ and $B$ in the following taxonomic hierarchy:
Kingdom $\rightarrow$ Phylum $\rightarrow$ $[A]$ $\rightarrow$ Order $\rightarrow$ $[B]$

Four statements are given below regarding the nomenclature of organisms. Which two statements are correct?
$(1)$ The first name denotes the species and the second denotes the genus.
$(2)$ $A$ species name used for one organism cannot be used for another organism.
$(3)$ Each word in a handwritten scientific name must be underlined.
$(4)$ It is mandatory to write the sub-species name after the species name for every organism.

What is the taxonomic category formed by a group of related genera?

What is a $Holotype$?

In plant classification,the order generally ends with . . . . . . .

Select the correct statements $(i-iv)$ regarding taxonomic categories.
$(i)$ Each step or rank in the hierarchy is called a taxonomic category.
$(ii)$ Species is a group of individual organisms with fundamental similarities capable of breeding among themselves.
$(iii)$ Taxonomic studies of all known organisms have led to the development of common categories like kingdom,phylum or division,class,order,family,genus and species.
$(iv)$ Lower the category,greater is the difficulty of determining the relationship to other taxa at the same level.