Looking at the column, let's say A3 is a white circle: that would be the last one, since you can have 4 white circles and 4 black circles maximum in the same column.
Having all the white circles placed, other cells have to be black circles: that would make the column output like:
A3-White B3-Black C3-White D3-Black E3-Black F3-Black G3-White H3-White
This means the column would result having 3 adjacent black circles, that is incorrect. Swapping A3-Black and B3-White would end up with the same result (3 adjacent black circles), so A3 and B3 have to be both black.
Sorry for my bad english, hope this can help!