write a reply indicating

 (a) the central or important point made,

 (b) an analysis or explanation of this point,

 (c) whether you agree or disagree with their response,

 (d) why you agree or disagree with their response by providing reasons. 

In other words: 

(1) Identify one issue and whether they agree/disagree.

 (2) Discuss, explain, or analyze the ONE issue identified—not many. 

 (3) Provide reasons for agreeing or disagreeing

The reply must be a minimum of 200 words.