The crossing-out of the D
-d octave at the beginning of the bar, visible in A, suggests that moving the bass line in b. 37-40 an octave lower (with respect to the version of FCI) was an idea born in the process of writing A or fresh enough for Chopin to commit a mistake in the first of the lowered octaves. In A we can see a crossed-out 
before the first d2 note in the R.H., which is an example of Chopin's uncertainty as to the key signature.
Compare the passage in the sources»
category imprint: Corrections & alterations; Source & stylistic information
issues: Corrections in A, Deletions in A, Bass register changes, Last key signature sign
notation: Pitch