Question

in 1915, the united states neutral stance was tested when germany asked mexico to attack the united states. sank the passenger ship lusitania. broke a deal to limit submarine warfare. signed the treaty of brest - litovsk with russia.

Explanation:

In 1915, Germany sank the British - owned passenger ship Lusitania, which had American passengers on board. This act tested the US neutral stance during World War I. The Zimmermann Telegram (asking Mexico to attack the US) was in 1917, the deal - breaking regarding submarine warfare was later, and the Treaty of Brest - Litovsk was in 1918.

Answer:

sank the passenger ship Lusitania