About 2000 years ago , Aristotle classified living organisms based on their movement - organisms that could move were classified as animals and those that could not were classified as plants . Animals were then divided into blood and bloodless ( not having red blood ) animals . He also classified organisms as those that lived on land , water , or in air . Furthermore , based on their ability to fly , swim , crawl , or walk , animals were classified as birds , fish , reptiles , and so on .
Which of the following best explains the limitations of Aristotle ' s classification system ?
A .
The classification was only based on the difference in the body sizes of organisms .
B . The classification was based more on external appearance and not on the internal anatomy of organisms .
C .
The classification was only based on the types of locomotion shown by organisms .
D .
The classification was based more on behavior and not on the structural comparisons between organisms .