Answer (A)-They helped the war effort in many different ways.
Explanation:
Answer: C.
Explanation: The Immigration Act of 1924 limited the number of immigrants allowed entry into the United States through a national origins quota.
A) An amendment is a formal change to law
Unrestricted submarine warfare is a type of naval warfare in which submarines sink vessels such as freighters and tankers without warning, as opposed to attacks per prize rules (also known as "cruiser rules").