No flaw. If David and Jane often disagree about whether they think a tree is a beech or an elm, then it has to be true that at least one of them is using an incorrect method for deciding whether a tree is a beech or an elm.

No flaw. If Jane’s description of the tree is consistent with her opinion of the tree being an elm, and David thinks the tree is a beech, then Jane’s description has to, in some way, be inconsistent with David calling the tree a beech.

Wrong flaw. (C) doesn’t rule out the possibility that both David and Jane could be wrong, so no dichotomy is presented. Alternatively, the stimulus argues that one theory must be right and the other wrong, which is the cookie-cutter “false dichotomy” flaw.

No flaw. By definition, David’s view must either be true or false. (D) just points this out.

David says a tree is a beech and Jane says it’s an elm. The argument in (E) says that when Maria gives her opinion, it’ll either verify David’s of Jane’s opinion. However, it’s possible Maria’s opinion will verify neither David nor Jane. (E) commits the same “false dichotomy” flaw as the stimulus.