Mesoamerica or North America?
If you get any Mesoamerican believers, follow up with:
Do you think the Book of Mormon Cumorah was in New York or southern Mexico?
If they say Mexico, you'll be tempted to ask what they think of Oliver Cowdery and David Whitmer, but I recommend against starting a discussion about it. This is a survey. Just see what people think.
Of course, if they want to discuss it, you know what to say.
So far, I've never met anyone who thinks Cumorah was in Mexico, apart from those who write for FARMS/Maxwell Institute, BMAF, and FairMormon and a few people who believe what those writers claim. Most people accept what Oliver Cowdery and every other contemporary of Joseph Smith did; i.e., that there is one Cumorah and it's in New York.