This exercise is about showing how different coloured filters affect how the primary colours appear when the image is shown in black and white. A blue filter for example will allow blue light through, effectively lightening it, but will to some degree block and darken the complementary colour on the opposite side of the colour circle - in this case yellow. Conversely a yellow filter will allow yellow through but block (darken) blue.
The yellow filter creates the most subtle effects I believe, as it lightens an already light colour; the green filter is also quite subtle - whereas the blue filter and to a slightly lesser extent, the red filter have the greatest effect. I created the effects basing it on the images shown in the coursework and also from my own research about how the various filters affect the tones of colours in black and white images. The Lightroom presets were too harsh to use in this exercise mainly because the original image was quite low key already.