<em>by identifying the topic, medium, and supporting sentences </em>This is the correct answer.
The topic, the development -or medium- and the sentences that support the topic are the key elements in an argumentation. These elements make up the central idea of the text. For example, if a speaker says : (1)" Using cellphones in a language class can help teenagers improve their writing skills"; (2)" I did some research in a language class and could see that how teenagers took done notes with the word application and then turned those notes into a paragraph."; (3) " Cellphones are used by teenagers all day long. They write a lot on them and this practice can be turned into a more academic activity."
(1) this reflects the topic: the pedagogical use of cellphones in a teenage language class;
(2) this shows the medium: some evidence through some real examples;
(3) This reflects some support to the topic.
These answers are not right:
-by asking the speaker to repeat all main ideas after he or she is done speaking ( This is impossible. The speaker will never do this in a conference , for example).
-by looking at notes kept by a peer who uses highlighting ( Note-taking is a personal task. The peer may have got the ideas wrong).
-by listening carefully to pauses the speaker uses when speaking ( Pauses will not help pick up the coherence of the speech).
