The Inflation Laboratory - Anna's Shoe Evaluation (WMV)

Anna tries out a few different pairs of shoes, this time using the bellows foot pump. She begins with a pair of flat thong sandals, and demonstrates a surprising ability to curl her toes backwards. She next tries a pair of mid-heeled slide sandals, and then a pair of low-heeled open-backed thong sandals, and lastly, a pair of black closed-toe flats. None of them slow her down in the least. Which ones will she choose for comfort and effectiveness?