Huynh, my style of helping students who as for a score is to score you on an individual basis so that I can fully explain how you made the mistake and how you can fix it. Based on this essay, I can see your potential as an writer and the problems you currently have which you need to address.  
  
Let me start by saying that you need to understand the difference between an ordinary opinion essay and a direct opinion essay. The IELTS test Task 2 is always a single opinion essay unless varied by 2 methods. The first variation is the "compare and contrast" essay and the other, is the "direct question , direct response" essay. The prompt you were provided with falls under the latter description. So, where is the problem then with your essay?  
  
A direct response / opinion essay requires you to immediately start the discussion in the opening paraphrase by allowing you to outline the 3 discussion points that you wish to present in the body of paragraphs. Here lies the difference with the other task 2 essays which do not allow you to begin the opinion discussion in the first paragraph. In the direct question essay, your must outline your response as part of your thesis statement in relation to its positioning in the body paragraphs presentation. The format that you followed here was the one for the ordinary essay opinion discussion. Please remember this difference for your future reference.  
  
Now for the scoring section of your essay. My scoring for this will be as follows:  
  
TA - 5 - you present relevant ideas in the discussion but these ideas are not totally threshed out in the presentation. The reasoning presented is limited in scope and does not always connect within the overall discussion. Using more transition sentences at the end of the paragraphs should help resolve this issue. Make sure that all of the discussion points presented in the prompt are appropriately responded to.  
  
C&C - 5 - You need to learn to develop your discussions in a more believable manner. The best way to do this is by presenting a singular discussion topic per paragraph. That way you have 4 sentences with which to fully explain yourself and why you support such a statement. What I read in this essay are all reference points for discussions which were never fully developed for the benefit of the reader. The reasoning is weak and the supporting statements require further explanations.  
  
LR - 5 - There are errors in your word formation and usage which affect the timeline (tense presentation) in the essay. This makes it very difficult for the reader to make sense of your paragraphs.  
  
GRA - 5 - your grammatical errors stemming from inappropriate word usage and sentence formation problems. You do not really have a proper mix of simple and complex sentence structures. Long sentences (run-on) that combine 2 ideas in one statement, separated by commas make it difficult to keep track of the message of the sentences and create forgettable paragraphs. This creates confusion for the reader who cannot remember what the discussion topic and reasons were all about.  
  
Please remember that there is a 3 sentence minimum with a 5 sentence maximum per paragraph presentation. Do not try to include too many ideas in your discussion if you wish to create an understandable and memorable essay discussion.