Which sentence is the thesis in this paragraph?

Some people think that healthy snacks lack flavor, but that is not true. Popcorn, which was first enjoyed by the people of Peru over five thousand years ago, is not only healthy but also quite delicious. The high rate of popcorn consumption among Americans supports this claim. Because popcorn is relatively high in nutritional value, is fairly inexpensive, and lends itself to a variety of cooking methods, it is one of the most popular American snack foods.