Which rules must animal taxonomists follow?

Identify the true statements from below $:-$
$(a)$ Convolvulaceae and Solanaceae belong to the same order
$(b)$ Animals,mammals,and dogs represent different taxa at same levels
$(c)$ Musca domestica is the scientific name of housefly
$(d)$ Taxonomic categories are distinct biological entities

Select the correct option for $Panthera$ $leo$,$Panthera$ $pardus$,and $Panthera$ $tigris$.

Which of the following is a taxon?

What is the smallest unit of classification?

Assertion $-A$: The term 'genus' is a single term.
Reason $-R$: $A$ genus may have one or more species; a species may be a single or a combined term.