The general approach is to firstly analyze the original sentence ( = answer A) and look for 0-2 grammatical or stylistic errors. You need to look for little red flags in the sentence, e.g. pronouns, tenses, Subject Verb Agreement, parallel structures, etc.
Once you have identified the mistakes in the original sentence, you should check whether they are not repeated in any other answer. Usually it will be easy to eliminate two or three answers only in these two steps. Later you move on to the remaining answers and check whether they contain any red flags and/ or mistakes. If you see that one answer includes a grammatical mistake and another choice is stylistically flawed, you should firstly get rid of the one with the grammatical problem.
Generally, we should eliminate answers that contain different types of mistakes in the following order:
1. mistakes with regard to grammar and logic
2. stylistic flaws
3. change in meaning
4. the underlined part does not fit to the non-underlined part of the sentence
