The first section, A, is played once with the trumpet and repeated once more without the trumpet. Its form is a, a', four measures each, forming a parallel period, and it is in D Major. The first phrase ends in an HC, and the second phrase ends in a PAC.
The second section, B, is also 8 measures and played once with the trumpet and again without it. The form is b,b' in D Major, but the first phrase ends in a IAC, and the second, a HC.
At this point it returns back to A, played once by the trumpet and again with just the organ.
Then comes section C, also 8 measures played once with trumpet and again without. Each phrase is still 4 measures long and it is c,c' However, this time the first phrase is in D major and ends on an HC and the second phrase is in A major and ends on a PAC.
It then returns to A, with a slight change in that it is played first without trumpet, and then again with trumpet, ending the piece on a strong PAC.
In a few ways, this rondo differs from "typical" rondos in a few ways. It is ABACA form, but unlike many pieces, the A form is played out completely each time it comes up, instead of shortening it. Also, while the C section does modulate to V eventually, neither the B nor C sections modulate as we expect them to. One additional difference is a lack of a transition or retransition anywhere in the piece.