Which of the following plants belongs to the order Rosales?

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

Select the correct statements $(i-iv)$ regarding taxonomic categories.
$(i)$ Each step or rank in hierarchy is called taxonomic category.
$(ii)$ Species is a group of individual organisms with fundamental similarities capable of breeding among themselves.
$(iii)$ Taxonomic studies of all unknown 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.

Assertion $(A)$: Maize is included in the class Monocotyledonae.
Reason $(R)$: This class does not contain any orders.

All the orders together constitute which of the following?

Cytotaxonomy is connected with