How do i do this question?
direct evidence~it is the most reliable in reconstructing the events to the source; due to an eyeeitness taking part in the event or action.
indirect evidence~this source is written sometime after the event--the author may have lived during the event itself.
artifact evidence~they're an interpretation of what happened. although the objects or images may have been created at the time of event, its not as good as direct evidence.

to fight against injustice and class division

necessary and proper clause. the congress shall have power to all laws which shall be necessary and proper for carrying into execution the foregoing powers, and all other powers vested by this constitution in the government of the united states, or in any department or officer thereof.

the speech revealed that eastern european countries were no threat to their neighbors, which led to the creation of the truman doctrine i think this might be correct.