[A] Preset – This changes between different Presets that Illustrator offers. Generally it is a good way to start, but will still require tweaking.
[B] Mode – This will switch from black and white, grayscale, or to color.
[C] Threshold – In black and White mode this changes the threshold between what is considered black and white.
[D] Palette – Either uses Automatic color selection or you can specify your own colors.
[E] Max Colors – Changes the maximum amount of colors used in the computations.
[F] Output to Swatches – Will output the colors used in the computations to your swatches palette.
[G] Blur – Specifies how much Gaussian blur is applied to the image before the computer tries and find edges. The more blur, the more general your shapes will become.
[H] Resample – Changes the resolution of the source image being used. This will help with performance and will change results in some cases.
[I] Fills/ Strokes – Toggles if fills or strokes are to be used in the render.
[J] Max Stroke Weight – Specifies that anything larger than this value will be considered a fill.
[K] Min Stroke Length – The smallest size of a stroke allowed, anything smaller is omitted.
[L] Path Fitting – Lower values create tighter maintained paths, higher values will create more relaxed paths.
[M] Minimum Area – You guessed it, the smallest detail that will be traced.
[N] Corner Angle – The sharpest corner angle allowed. (In degrees)
[O] Ignore White – It omits white from the calculations, and therefore leaves white areas transparent.