Answer:
Authors may reference similar stories to compare the similar story to their own story either for sales, or just pure comparison.
They are fighting because they are rivals.
Answer:
It helps to come up with topics and ideas
The correct answers would be questions D " Did any of the Japanese or German students learn to speak Navajo" and E " What kind of code did the American Indians use during World War I". These are the questions that could help the reader understand the military leader's fear, since if the answers are yes they did learn to speak it, and a simple code, (respectively) then it would be perfectly sane to feel apprehension at using the same code again. Options A, B and C are not relevant because they do not contribute to the subject, for example, it doesn't matter how many people spoke Navajo before World War I, what is important is how many can learn it.
The answer to this question is A