Dear Arik, I want to tell you of an incident that happened when I was preparing for EAMCET. It is a State Level Entrance Examination for admission into Medical and Engineering colleges in Andhra Pradesh. One of the aspirants from the previous year scored 100% in the entrance examination. Now that was a wonder because the paper was tough. So, the authorities decided to see how he/she scored 100%. What they saw was the most foolish act by a student. He/she rounded of all the options for every answer in the OMR. For example, for Question no. 1, he chose all the answers and rounded off A,B,C,D with the pencil. So ideally, there will be one right answer for every question and the Electronic correcting system will check if the right answer is chosen or not and that's how he/she scored 100%. What happened later is irrelevant but that's an example of smartness taking a wrong route. Now coming to your question, you know that is a silly mistake to commit and when it is about your career, it is a grave mistake. Even going by the rule of probabilities, you cannot predict the outcome of an event until the results are there for everyone to see. You might get 80+ or might not get 80+. But your question should be is it worth wasting an attempt trying to give it to throw a stone in the dark. If it hits then its fine but if you miss it, you lose an attempt. 

No it is not beneficial because if you just take all the options same then according to the probability you will get around 25 marks at Max and even though if you make changes to some of the options then it will be difficult to find the questions in which you would like to make the changes therefore the best strategy is just select those questions in which you are hundred percent sure and  even if you attemp Just 20 questions of that type then also you will score 80 marks.

Hello,

I would like to tell you that there are various paper codes and all of the have the options jumbled up in a different manner.

So maybe some set may have a lot of correct answers in B while some may have  alot of wrong answers in B.

I would suggest you to check the solutions online regarding to your paper code and then check as it cannot be predicted.

If you have any more doubts then you can comment down your query.

Hope this helps and all the very best !