Thanks! We will be adding more questions soon. Researching and formulating good questions is somewhat of a slow process. We're thinking of either posting 1 question everyday or posting a batch of them every week. We're going to try both approaches to see what works.
"How many animal species are headed for extinction?"
The correct answer is almost certainly 100%, but this is not even available as an option. Without any time horizon specified, any value less than 100% is not really meaningful.