What were three reasons that the German government restored to submarines warfare?

Unrestricted submarine warfare was first introduced in World War I in early 1915, when Germany declared the area around the British Isles a war zone, in which all merchant ships, including those from neutral countries, would be attacked by the German navy. A string of attacks on merchant ships followed, culminating in the sinking of the British ship Lusitania by a German U-boat on May 7, 1915. Although the Lusitania was a British ship and it was carrying a supply of munitions—Germany used these two facts to justify the attack—it was principally a passenger ship, and the 1,201 people who drowned in its sinking included 128 Americans. The incident prompted U.S. President Woodrow Wilson to send a strongly worded note to the German government demanding an end to German attacks against unarmed merchant ships. 

the answer is c     : )

explanation:

i don't have an explanation because i don't know, but i think the answer is c because i googled it and google is right : ) just kidding google isn't allways right but the answer is still c. i hope this !

they made rome the dominant power in the mediterranean.