What did she remind me to do?

The correct answer is appropriate in this context if the specific detail about her reminding you to bring binoculars aligns with the situation described. For example, if you were planning an outing where binoculars would be necessary, and she specifically mentioned them, then this response accurately reflects the action she wanted you to remember.

The other choices might involve items that are also important but do not align with the context or what she specifically reminded you about in that situation. For instance, if the outing did not require a map, tickets, or a favorite book, those items would not be relevant reminders from her. Thus, the choice of binoculars makes sense if they were particularly emphasized in the conversation leading up to the reminder, highlighting their importance for the planned activity.