Within reason, the number of branch choices you list on your application has no detrimental impact on your assessment - but you do need to show that you know something about all of your choices in the interview. It doesn't matter whether you are going for a commission (in any branch) or NCA, if you pass the essential medical/aptitude requirements for your choices and go on to Part 2, you are all treated exactly the same! At the end OASC first of all decide whether you are selectable. The qualities looked for are the same for officer and NCA - it's the relative strengths and weaknesses that you display than determine whether you are more suited to one or the other, or to a particular branch - and your aptitude scores and level of fitness are all taken into account. If you are assessed as 'not selectable', you get a 'Sorry, no thank you this time' letter. If you are assessed as selectable, you are then considered for your branch choices, including NCA if applicable IN THE ORDER YOU SPECIFIED. Thus you are only looked at for your second (or third) choice if you have already been considered and rejected for your first (or first and second) choice(s). If you have only one choice, that's all you are considered for.