The answer is D. The first word indicates the organism's genus classification.
Binomial nomenclature is a formal system of naming species. As the word 'binomial' suggest, a name is composed of two parts. The first word indicates the organism's genus classification, the second word indicates the species within a genus.
The other statements cannot be true because of the following reasons:
B. The second word is always capitalized. - the first word is always capitalized
C. The first word is always lowercase. - the first word is always capitalized
D. The first word indicates the organism's genus classification. - the second word indicates the species within a genus.
