Which of the following statements is true about Germany's use of U-boats?
O
A U-boats sank ships carrying civilians.
O
B. U-boats had to surface to attack ships.
O
C. U-boats announced their presence to neutral ships.
O
D. U-boats attacked in daylight to leave more survivors.

On May 5, 1942, 29 Navajo men arrived at the Recruit Depot in San Diego for basic training. That was followed by intensive courses in transmitting messages and radio operation at the Fleet Marine Force Training Center at Camp Elliot. The 29 recruits developed the code with communications personnel during this training.

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