This is another one from the five you picked I like.
Because: - the girls in the white dresses. It's rather uncommon view and it's underlined by the numbers of girls - the interesting moment you caught - again makes me so hard to think, 'what on earth are they doing? praying? singing?'. The good photo always makes you wonder. That's what I believe!
Now the bad things. - sharpness, contrast, the light... They need improvements here and probably just another try. Still these are not a factors that could ruin the photo. I'd say just the little shortcomings. - the crop - I think it would be nice to have a bit more space in the upper and lower part, especially to see the whole legs.
And what I think you can do more about it.... Mind these are mine preferences, the post processing is always a matter of choice of the author. A bit brightening and a bit sharpening. Check how it looks like b&w, though mind that you have a strong point in the green blouse of the lady in the centre. Maybe it's a funny idea to leave only green coloured and the rest b&w? Also I like the skin tones compared to the white dresses. Maybe adding some fancy blur to make the girls look more angelic?
It is very dangerous for a dancer (ballet) to be exposed to 'flash'-On stage especially. There should be NO FLASH photography when in auditorium. I read your specs (EXIF) and while in the studio you should be able to bump the ISO down to at least 200, 400 (play with it) and still get your shutter speed to be fine at around 1/300 or above to freeze action. But when they are standing like this not a fast shutter is needed because they are not moving. The grainy is from the high ISO. The studio fluorescent lights suck - I know, but you can adjust your WB in PS. The lens your using at f1.8, 1/250, iso:3 - 400 should allow enough light in the camera - especially for a shot such as this.. no movement and shutter was 1600 - wayyy to much - Hope this helps - Regards cZ