Thanks! And agreed. There is exactly one right answer. And you can learn a lot about the test by figuring out why it was right and the wrong ones are wrong. But

Thanks! And agreed. There is exactly one right answer. And you can learn a lot about the test by figuring out why it was right and the wrong ones are wrong. But I say that with the caveat that it's not "clear" for everyone. I often had students who came up with very convincing but completely incorrect reasons for why they thought the right answer was right.