Question

taxonomic group of any rank is 1. class 2.order 3.taxon 4.phylum.​

Answer 1

A taxon is a taxonomic group or taxonomic unit. Each category is referred to as a unit of classification in fact, represents a rare and is commonly termed as taxon. Many modern systematics, such as advocates of phylogenetic nomenclature, use cladistic methods that require taxa to be monophyletic.  

The term taxon is a collection of more than one population of the organisms or organism seen by the taxonomists for forming a unit. There are seven main taxanomic ranks: kingdom, phylum or division, class, order, family, genus, species.

The term taxon was first used in 1926 by Adolf Meyer for animal groups, but the term taxon was coined by Linnaeus.  

So the correct option is taxon.