I had taken four subjects in my AS level, and got good grades in three of them, but unfortunately got a D in one of them, as this subject is not required for my course in university I dropped the subject and now I am pursing the other three subjects in my A levels.Usually majority of the universities require three A levels, which I have, but I am concerned how this D in one subject will effect my university admission when they will view my results. should I consider retaking the exams or there is another solution?