I think it was the:
Civil Rights Act
The Civil Rights Act of 1957 was passed in order to make sure that all
Americans could exercise their right to vote. It was the first civil
rights legislation passed since reconstruction. Its enactment also came after African Americans were increasingly targeted with violence following the U.S. Supreme Court’s Brown v. Board of Education decision ending segregation in schools. The law showed a renewed national attention to
guaranteeing civil rights to all Americans. In addition, it established the Commission on Civil Rights, a federal oversight committee that examined opinions of the public and state laws regarding civil rights.
Aid to Viet Cong.
We were fighting against the Viet Cong, not aiding them.
Nationalism motivated thousands of states, at the same time, turned self-interest and lust of power led to severe fall of mankind.
The correct answer is D.
Although the RMS Lusitania was a British ship, when it was sunk by a German submarine in 1915, 234 American citizens died. Nevertheless, in 1916 the Sussex Pledge took place, being a promise made by Germany in which they claimed to attack with no previous warning any armed ship. However, in March 1916 Germany torpeded a French ship that had no weapons, meaning this, and announcing Germany the resimption of unrestricted submarine warfare. Finally, based on the German decission and having reasons because of the Lusitania deceased people, the US declares war on Germany in April 1917.