What is a species?

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.

Which of the following is a species?

Which of the following is the order of maize?

Plant families like $Convolvulaceae$ and $Solanaceae$ are included in the order $Polymoniales$ mainly based on their . . . . . . characters.

When writing scientific names by hand,what is drawn under each word?