The passage mainly discusses how ____________

Câu hỏi: Read the following passage and mark the letter A, B, C or D to indicate the correct answer to each of the questions from 35 to 42
Diffusion, the process of introducing cultural elements from one society into another, occurs in three basic patterns: direct contact, intermediate contact, and stimulus diffusion.
In direct contact, elements of a society's culture may be adopted first by neighboring societies and then gradually spread farther afield. The spread of the manufacture of paper is an example of extensive diffusion by direct contact. The invention of paper is attributed to the Chinese Ts'ai Lun in A.D. 105. Within fifty years, paper was being made in many places in central China. By 264 it was found in Chinese Turkmenistan, and from then on the successive places of manufacture were Samarkand (751), Baghdad (793), Egypt (about 900), Morocco (about 1100), and France (1189). In general, the pattern of accepting the borrowed invention was the same everywhere. Paper was first imported into each area as a luxury, then in ever-expanding quantities as a staple product. Finally, usually within one to three centuries, local manufacture started.
Diffusion by intermediated contact occurs through the agency of third parties. Frequently, traders carry a cultural trait from the society that originated it to another group. As an example of diffusion through intermediaries, Phoenician traders spread the alphabet, which may have been invented by another Semitic group, to Greece. At times, soldiers serve as intermediaries in spreading a culture trait. During the Middle Ages, European soldiers acted as intermediaries in two ways: they carried European culture to Arab societies of North Africa and brought Arab culture back to Europe. In the nineteenth century Western missionaries brought Western-style clothing to such places as Africa and the Pacific islands.
In stimulus diffusion, knowledge of a trait belonging to another culture stimulates the invention or development of a local equivalent. A classic example of stimulus diffusion is the creation of the Cherokee syllabic writing system by a Native American named Sequoya. Sequoya got the idea from his contact with the English; yet he did not adopt the writing system nor did he even learn to write English. He utilized some English alphabetic symbols, altered others, and invented new ones. All the symbols he used represented Cherokee syllables and had a distinctly Cherokee form.
The passage mainly discusses how ____________
A. cultures retain their unique characteristics
B. cultural elements transfer from one culture to another
C. paper came into general use
D. economies grew through trade and manufacturing