Which group discussion technique is best illustrated by the following statement?

of course the author is going to support a liberal immigration he's trying to immigrate to america. i just think this makes him too biased to consider the issue fairly.
a. restating an idea to ensure understanding
b. disagreeing respectfully
c. challenging established ideas
d. holding group members accountable

C. challenging established ideas

Explanation:

The established idea the speaker is challenging is the issue concerned with a liberal immigration policy. This idea, in the speaker's view,  is being supported by an author who is trying to emmigrate himself to America. Therefore ,there is no point in discussing about a policy to allow  free immigration if this idea will be supported by an author directly affected by the situation. The speaker puts it in these words: "..to consider the issue fairly."

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explanation: