About the question you asked earlier: It is important to know what species an organism because if we didn't, we would just get everything mixed up. There are 10,000 species of bird in this world, and imagine if we just called them all, "bird." or if we just called imagine if we called all ants "small insects." To name them, Scientists use a two-name system called a Binomial Naming System. Scientists name animals and plants using the system that describes the genus and species of the organism. The first word is the genus and the second is the species.
For the question on here: D, A, B, C.