The answer is D (revive forgiveness for sins )
This site will probably help you, hope this help.
http://www.shmoop.com/esperanza-rising/marta.html
The correct answer is letter C.
Explanation: Nubia could use elements of Egyptian culture to create its own imperial power. Nubia has been in constant contact with Egypt for much of its history, and Egypt has at various times advanced the region with military and colonizing expeditions. Nubia, however, has developed independently of Egypt since prehistory.
Silk I believe, I might be incorrect though.
Answer:
it was useful because this could have helped with navigation purposes, for example, traveling from country to country by sea
