Capitalization on selectable answer words.
I suggest you do NOT capitalize any selectable words in the solution to a question. It does lead you to a correct answer, but, in my opinion, it makes it too easy in many cases.
I agree, it's an absolute tell. But then the selection of words is itself an absolute tell most of the time. Once you've become a little familiar with the material it's a good idea to click on "make harder" which takes the tiles away and makes you type in the answer from scratch.
Bear in mind that the design of the lessons is intended to give the learner heavy hints in the early stages, so they can pick the right word, and then the hints get less and less obvious until you're doing it with no hints at all. You do have the choice to get rid of these hints if you feel you're ready.