What did it take to convince Lt. Col. James E. Jones that using Navajo codes would work?

A. An experiment proved the speed and accuracy of Navajo codes was better than the code that was commonly
used by the Marines' Signal Corps.

B. The security of the Navajo code was intensely examined and analyzed
cryptography experts who failed to break it.

C. Lt. Col. Jones had known Navajo Philip Johnston for many years, and trusted his
recommendations.

D. The Navajo language was simple, and it would be easy for English-sp
Marines to learn and use.