The tiger argument requires outside knowledge which can be seen as an assumption on the LSAT if not used carefully. Using outside knowledge can leave room for mistakes.

The second argument about the Walt is very solid. There are set rules in place which make it extremely difficult to come up with a different conclusion.

The third argument is a hypothetical situation, just like a hypothesis in a science project; it is not guaranteed to be true although there's a good amount of evidence. There's still room for error. However, that seems like the most correct conclusion based on the hypothesis.