The correct answer is A) since few people understand it, it is a difficult code to break.
One advantage of using Navajo as a military code language is, “since few people understand it, it is a difficult code to break.”
The military has to develop new, different, and complex codes of communication in order to avoid the enemy intercept them and interpret them. It is a national security strategy. During World Word II, the U.S. Navy develop an ultra complex code called Navajo. Previously, in World War I, the Army used another difficult language: Choctaw.