The original purpose of the Constitutional Convention of 1787 was to "A. revise the Articles of Confederation" since the Articles were far too "weak" for an effective government.
Answer: Miranda vs. Arizona - 5th amendment
Brown vs. Board of Education - Segregation was unconstitutional.
Marbury vs. Madison - U.S. Government must function...
Plessy vs. Ferguson - Segregation is constitutional.
Explanation: Here are some videos further explaining the cases!
Miranda vs. Arizona - https://youtu.be/FJ7ooBJ_DEU
Brown vs. Board of Education - https://youtu.be/4F4edxloXCc
Marbury vs. Madison - https://youtu.be/GLTCf1NMAj4
Plessy vs. Ferguson - https://youtu.be/vsDTqtyiNZk
The primary mission of Al-Qaeda during this time was "to force the Soviet Union's troops out of Afghanistan," since the failed Soviet invasion of this region helped unite many potential supporters of the Al-Qaeda movement.
The question will be true! :D