Answer: The correct answer for the blank is-
a description of a trait or habitat.
According to the binomial system of classification, living organisms can be named scientifically, using two words. The first word in the scientific name of the organism corresponds to the Genus and the second word/ part is the species to which the organism belongs. The second part that is the species depicts the description of a trait or habitat.
For example- Scientific name for Human beings is Homo sapiens, which shows that they belong to species 'sapiens' that gives description of human beings.
Thus, first option is the right answer.