The __ caused the united states to enter world war i.

1.) revolution in russia
2.) assassination of archduke ferdinand
3.) german attack on belgium (not the answer i tried this)
4.) telegram and sinking of american ships

telegram and sinking of the American ships

Explanation:

Germany started sinking US ships which angered the president. The Zimmerman note added to this. Arthur Zimmerman sent a telegram to Mexico which was intercepted by the British. It said if Mexico joined the war against the US then after victory they would return some of its territory back. That was the final push that led to the US to enter World War 1.

b is the answer i am assuming

most people now work in jobs where they do one  kind  of work; they are carpenters, bankers, cooks, mechanics, and so forth. likewise, most  businesses produce  only certainkinds  of  goods  or  services, such as cars, tacos, or gardening  services. this feature of  production  is known as specialization.