This movement is in Bb Major and the primary section starts out with a HC at measure 4 and a PAC at 8. This is expository material that is just essentially repeated twice. Next is a transitional area that brings the movement to the dominant at measure 21.
The alternating section is 21-41 where the tonality is a little less structured. There's a PAC at 36, and then a 4 bar transition back into A material in the dominant key. This is basically identical to the first A section.
The C section is much louder and in d minor which is the relative minor to the dominant of the original key. There is a PAC at the end of the first 8 bars of the section. There is alot more chromaticisim going on after that which ultimately brings us back to Bb major and the A section once again.
The D section is somewhat similar to B but not similar enough, So it's stil D....deal with it. It feels as though Mozart has returned to the A section at 173, but he was joking....he finally transitions at 189 bringing us back into A.