Why did German U-boats not warn their targets before sinking…

Why did German U-boats not warn their targets before sinking them, as outlined in the standard rules of warfare? a.    Because they were dirty rotten bastards. b.    Because U-boats can only fire while underwater. c.    Because the British urged merchant ships to install guns and fire on or ram U-boats. d.    Because the official rules of warfare were changed in an international conference.

After sinking the Arabic in August 1915, the Germans agreed…

After sinking the Arabic in August 1915, the Germans agreed to the Arabic Pledge, which stated…. A. That the Germans would, essentially, stop sinking all ships. B.  That the Germans would not sink passenger liners without warning. C.  That the Germans would sink any and all ships that its U-boats found. D.  That the Germans U-boat commanders would learn the Arabic language.