What is the IUPAC name of Hexamethylenediamine?

Hexane-1,4-diamine Hexane-1,5-diamine Hexane-1,6-diamine Hexane-1,3-diamine

Hexane-1,6-diamine

The formula is NH2-(CH2)6-NH2 which is the chain of 6 carbon atoms and two amino groups at the ends of the chain, i.e., first and sixth carbon. This type of substitution is named and hexamethylene.