Response to @paulg status 1580500170776535042

Note: I'll be using musical notation, calling each circle a 'note', each set of notes a 'chord', and each interval between possible positions of notes a 'step'.

Observation #1: In the original sequence, each note moves at most two half-steps from one chord to the next.  But in answer A the middle note moves *three* steps up, so A can be eliminated.

Observation #2: The chords always change from one to the next. So D can be eliminated, because it would be a repeat of the last chord in the provided sequence.

Observation #3: The relative distances of the notes within each chord are always changing from one to the next.  So E can be eliminated because the distances between the notes in the chord are identical to those in the last chord in the provided sequence (in other words, the entire chord has just been moved up one half-step).

This leaves us with B and C.

Observation #4: There is an alternating "expand and contract" pattern among the notes of each chord from one chord to the next. From chord 1 to 2 the chord contracts (the notes get closer together), then from 2 to 3 it expands, then from 3 to 4 it contracts, and from 4 to 5 it expands.  So I would expect the missing chord to show a contraction of the distances of the outer notes from the middle note. B shows an expansion, while C shows something closer to a contraction.  But it doesn't quite work because the bottom note in C is at least a half-step lower than I would expect it to be.