The correct option is A Key
Keys are taxonomical aids used to identify plants and animals based on the similarities and variations. The keys contain contrasting characters, commonly in a pair called a couplet, which portrays the choice made between two opposing options. This results in the approval of only one and the dismissal of the other option. A statement in a key is termed a lead. Each taxonomic category, such as family, genus, and species requires separate taxonomic keys for identification purposes.
Manuals contain the names of species found in a particular area. They are useful in providing information for identification of names of species found in an area.
Flora contains the descriptions of the habitat and distribution of plant species found in a specific area.
Monographs are taxonomical aids that contain the information of only one taxon.