Which one of these is an example of an open-ended question

An Open-ended questions is considered as the questions that cannot be answered with a simple "yes" or "no". It required a more detailed response and then compared with the data known by the questioner.
So, the correct option is D. "How did your ancestors get their wagons across the rivers."
Open-ended questions prompt the beginning of a longer conversation by asking questions starting with "why," "how.". Like in this case the question starts from "How".
To know more about Open-Ended Questions, refer to the link:
https://brainly.com/question/5967925