Rhythm of the "little a" section
Notice how the motive is quarter note, dotted eighth/sixteenth notes, and two quarter notes...
Rhythm of the "little b" section
The motive gets turned backwards and slightly altered here...
Rhythm of the "little c" section
Total contrast. The quarter notes in the first and third measures smooth things out after all the dotted eighth/sixteenth note rhythms. However, so we don't forget them, those rhythms show up again in the second measure even more so than before.