Why did the United States break diplomatic relations with Germany in 1917?

A. Germany refused to accept President Wilson’s Fourteen Points.
B. Germany signed the Treaty of Brest-Litovsk with Russian Bolsheviks.
C. Germany declared unrestricted submarine warfare against all ships.
D. Germany sank the British liners Lusitania and Arabic in quick succession.
E. Germany offered to help Mexico recover Texas, New Mexico, and Arizona.