It is always useful to diagram both the argument and the contrapositive when answering any type of question to avoid any confusion regarding what can logically be concluded while working through the answer choices.
Sometimes, Must Be True questions will pertain to the contrapositive as opposed to the direct argument. If you have already mapped this out, then it will be easier to select the correct answer choice as you have visual representations in front of you.
Additionally, questions will sometimes try to trick you by simply reversing or simply negating the original claim. If you have already mapped out both the argument and the contrapositive, then you can safely eliminate these trick choices.
Overall, you should always diagram both the argument and the contrapositive when answering any type of question. While not all questions will require you to examine both, it is always helpful to have a visual representation of the argument in front of you to avoid making mistakes.
Hope this is helpful! Please let us know if you have any further questions.
