The answer is b african slave merchants
Explanation:
After the build up of tension from Nationalism, Imperialism and Militarism, the Powers were worried about being attacked by each other. To counter this alliances were formed. ... The Alliance System was definitely a prominent cause of WWI. If Germany hadn't allied with Austria the war might've been averted.
According to the National Archives "The Constitution provides that an amendment may be proposed either by the Congress with a two-thirds majority vote in both the House of Representatives and the Senate or by a constitutional convention called for by two-thirds of the State legislatures."
So, this provides for a Federal and a State option for passing amendments.