What is the most healthiest snack in the world?

Without having done research (this answer can/should be improved with facts), I'd have to guess that in the U.S. it's either popcorn, because it's generic, inexpensive and sold in massive quantities in movie theaters, or potato chips because there are so many brands and flavors competing for the market space.

...and it turns out that I'm wrong. According to the study I found (link below), kids actually snack on fresh fruit more than anything else. As for adults, the first 4 are gum (not really a food), chocolate candy, fresh fruit and...potato chips.

Answer: Potato chips