The correct option is C, as military commanders used codes to communicate secretly.
These messages were transmitted, usually by telephone or radio, using codes built on strange languages, known to small groups, sometimes dozens of people around the world, which was a great strategic advantage. This advantage lied in the fact that military codes could be broken or deciphered with relative ease, whereas such a minority human language required a long process of study in order to understand it.
Code talking is strongly associated with Navajo Indians, who used their language to send secret military messages during the First World War and the Second World War, serving as a great help to the US Army, mainly in the Pacific area. Other Native American code talkers belonged to peoples like the Cherokee, the Choctaw or the Comanche, also served in the US military in areas where it was not expected that anyone understood their language.
