In ancient times, silk was a valuable good for China to trade because A. the journey eastward to obtain it was dangerous
B. it could be made into colorful silk banners.
C. it wore out quickly and had to be replaced
D. only the Chinese knew how to make it.

D only the Chinese knew how to make it!

Explanation: Thank you for asking and have great luck!

americans had many intangible advantages. well since the british fought a war far from home military orders, troops, and supplies sometimes took months to reach their destinations, and the british had an extremely difficult objective. they had to persuade the americans to give up their claims of independence, americans had a grand cause: fighting for their rights, their independence and their liberty. this cause is much more just than waging a war to deny independence.

genetics is the study of how dna works, the methodologies defining the new recent technologies allow scientist to have a panoramic view of the entire dna landscape, especially how genomes interact with their environment, including off course, factors outside their organisms.

thus is very possible the existence of both scenarios, where populations of isolated individuals have different genetic traits, and share traits related to genetic mutation, due rats can easily travel overseas using human transport channels. so scientists could get a vast number of data, including human interaction, evolution of rodents, health development, spread of infections, development of new organisms, how genomes evolve in different environments and so on.