I conducted my own experiment with my flat mates and these were the responses:
The reasons behind the choices:
1) "This is the most eligible choice and i think it is right, I'm not really into art but this looks right to me"
2) "This is definitely the right colours, the primary colours have to go in order and these are the colours that I would associate with the shapes"
3) "I'm not too sure, but I think that these colours are right"