Comment by tripzilch

Are you sure that it is common practice for a problem that has three valid answers A, B and C, to only allow people to answer A or C?

Your website is not talking about "levels" of colour.

It's asking "is this blue or green", not "is this closer to blue or closer to green".

The question (1) "is this blue or green" has three valid answers: blue, green or neither.

The question (2) "is this closer to blue or green" only has two valid answers.

I would assume that with these types of surveys, the first thing to do is to qualify the proper categorization of the question.

Sorry to say, but to me it seems that almost all of the confusion in the discussion here is because you're asking question (1) (which has three valid answers) but expecting an answer from (2) (which indeed has two valid answers).