<image 1> A historian would use the above map to illustrate which of the following?
['Major trade routes in the classical era', 'The spread of communism from 1900 to today', 'One aspect of cultural diffusion', 'The monsoonal wind patterns of Asia']
The spread of religion is one of the best-known examples of cultural diffusion, and the map shows the spread of Buddhism. Trade routes (e.g., the Silk Roads) in the classical era (A) originated in China and continued to the Mediterranean. Communism (B) is primarily a twentieth-century phenomenon that did not originate in India. The paths shown have nothing to do with weather (D).