Congratulations on going for an ARCT as an adult student. This is a significant achievenment and goal and should serve as an inspiration for many others in your situation.
General comments about the exam that may influence your programme order and choices:
1. All pieces are played through without comment or prompts from the examiner. The candidate chooses the order of the pieces.
2. As a general note, all candidates are encouraged to leave enough time between each piece of the examination, as if they were going to bow, go offstage, and come back on.
3. You are allowed (and encouraged) to take a break approximately halfway through your examination. You may bring water, use the washroom, walk around ...etc. This is to represent am "intermission" of sorts.
5. YOU ARE GIVEN TIME TO TRY THE PIANO -- do take advantage of this. If the examiners don't offer, ask to try the piano. I would recommend you plan your piano trial in advance so you can maximize this time. You should aim to try out the instrument for no more than 2 minutes.
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On to the programme:
Because there are overlapping choices between the two programmes, I'll just briefly state my feelings about each of the options as I see fit.
Bach and Mozart: These are some of the more challenging options available on the syllabus. The Bach is very popular for younger candidates, as it can be played very fast and achieve great success. As an older student, my recommendation is to take a slower, more stylistic and intelligent route that considers more details ... this will help set your performance apart from your youth counterparts.
Prokofiev etude: Very challenging, but extremely effective if successful. I would use this to open your second "half" of your programme.
Barber: Personally, I'm not a big fan of these pieces, but they are played successfully in many examinations. Can be a great choice for people who prefer less avant-garde works. Another option would be the Bartok Sonatine.
List C: These are great masterworks of the romantic literature. That being said, I don't like these works for exams, as everyone has their own "correct" interpretation of these works. The examiner's reports from the 30+ candidates that I have read reflect these sentiments. However, this may not be the case for yourself, as you will have had significantly more life experience than these students, and this may help you better perform these works. In general, I don't like Schubert for exam situations, so I would go for a Chopin Nocture. You may also want to try one of the Liszt Sonnetti as an alternative option, or a Brahms Intermezzi.
List D: I personally would play Faure, as I tend to gravitate to his sound-world naturally. That being said, the Rachmaninov would provide more balance to a rather lyrical programne. The added advantage of the Rachmaninov is its ability to hide most minor imperfections in the texture ... which can be beneficial. Though this may be falling into the style of the Faure, you may want to consider the Op 32 no 12 (G# minor) prelude ... it is easier and also very effective. The Debussy Ballade may also be a good choice.
Again, Congratulations and best of luck in your exam