The questions in this group are based on the content of a passage. After reading the passage, choose the best answer to each question. Answer all questions following the passage on the basis of what is stated or implied in the passage.
Of all aspects of Indian culture, the caste system is perhaps the most bewildering to outsiders. For visitors unaccustomed to this system of hereditary social divisions, the complex and mostly unwritten rules governing whom a person can marry, what kind of work she can do, and even what kind of food she can eat may seem puzzling and mysterious. One reason for this confusion is that the concept of caste is actually divided into two separate but related concepts in Indian culture: varna and jati.
Varna, which literally means "color," is the most basic social division. There are four varna: the Brahmans, the traditional priest class; the Kshatriya, the warrior class; the Vaishya, the skilled workers and merchants; and the Sudra, laborers whose role is to serve the three higher classes. Below the Sudra are a class known as the Untouchables, who technically fall outside of the varna system because they are supposedly "unclean" in a ritual sense. The Untouchables are the lowest class in India, but they make life possible for everyone else because they take care of the jobs that would "pollute" the higher classes, such as working with dead animals or cleaning sewage. The Indian statesman Mohandas Gandhi, in an effort to promote social equality, encouraged people to refer to Untouchables as the Harijan, which means "Children of God."
Each varna is then divided into hundreds or thousands of jati, a term that literally means "birth." The jati are kinship groups with hereditary roles and professions, such as leatherworker or brick-maker. Observant Hindus have traditionally married within their varna and jati.
The origins of the caste system are obscure. The prevailing theory among anthropologists is that the Varna system emerged shortly after the so-called Aryan Invasion of the second millennium B.C. According to this theory, a population of Indo-European invaders conquered northern India around 1500 B.C. The Indo-Europeans placed themselves in the three highest rungs of society (Brahman, Kshatriya, and Vaishya), corresponding to the traditional division of Indo-European societies into priests, warriors, and commoners, while placing the conquered local populations into the worker classes of the Sudra and the Untouchables. This theory does not account for the jati system, however, which has parallels in no other Indo-European society. Most anthropologists suggest that the jati system predates the varna system, and that it might have originated in the Harappan civilization that prevailed in northern India prior to the Aryan Invasion.
The relationship of jati to varna is most comparable to which of the following relationships ？（）
A. The relationship of individual playing cards to a 52-card deck
B. The relationship of a group of related species of animals to the genus to which the species belong
C. The relationship of a compact disk to the songs contained on that disk
D. The relationship of a transmission to the car in which the transmission has been installed
E. The relationship of an updated version of software to the original version of that software
F的化学反应方程式为 。