Which statement best summarizes the work of the code talkers

The Navajo Code Talkers were a group of Native Americans who were recruited by the Marines during World War II. These individuals were recruited because of the their native language. In order to be successful in World War II, the US needed to be able to communicate strategic plans and important battle information at a rapid pace. Along with this, the language they used must not be able to be interpreted by enemy listeners. This is where the Navajo came in.

Their native language is almost completely oral (aka no written form) and extremely difficult to decipher. These code talkers helped to relay thousands of messages over the course of World War II.