Why is providing evidence to support your position an important part of building an argument?
a.
the speaker should provide evidence only when asked by the audience.
b.
the speaker does not have to provide any evidence to support his or her position.
c.
the speaker provides evidence only when discussing the opposition's side, during the rebuttal stage of a formal debate.
d.
providing evidence indicates that the person understands the issue, carefully thought about his or her position, and then found supporting research to defend that position in an effort to convince the audience.

the speech this question is referring to is president kennedy's special message to the congress on urgent national needs, may 25, 1961

kennedy responds in a very direct and concrete way to those thinking that communism is a positive system:

"yet their aggression is more often concealed than open. they have fired no missiles; and their troops are seldom seen. they send arms, agitators, aid, technicians and propaganda to every troubled area. but where fighting is required, it is usually done by others--by guerrillas striking at night, by assassins striking alone--assassins who have taken the lives of four thousand civil officers in the last twelve months in vietnam alone--by subversives and saboteurs and insurrectionists, who in some cases control whole areas inside of independent nations." (kennedy)

president kennedy presents communism as cowardly, as a hidden and treacherous weapon that strikes from the shadows like thieves, he represents the system as not even being capable of showing and open and overt attack or confrontation. to finish up the response, he expresses that the system attacks even a country's idependence and freedom.