Given a context passage, generate a question from the passage such that its answer is shortest continous span from the passage.

[EX Q]: Marcus Foligno (born August 10, 1991) is an American-Canadian professional ice hockey player, who plays for the Buffalo Sabres of the National Hockey League (NHL).
[EX A]: What team did Marcus Foligno play for?

[EX Q]: Yana De Leeuw (born 6 September 1990) is a Belgian female former volleyball player, playing as a setter.
[EX A]: Which sex or gender can Yana De Leeuw be described as?

[EX Q]: Vans, Keds, Dollies--they sound like the names of rock bands, but if you have teenagers, you'll know they're actually the latest in teenage footwear. But experts are now warning that the current shoe fashions will be causing teenagers discomfort in the short term and storing up years of foot, knee and back pain in the future. Here, the experts identify the problems caused by teenagers' shoe choice. KEDS/VANS Slip-on shoes with elastic sides are particularly popular among teenage boys-with Keds and Vans the most sought-after brands. The main problem is that they are just too flat--so flat that the heel, which strikes the ground first, also becomes damaged and painful. BALLET PUMPS The worst shoes of all are such light and thin dolly shoes. The problem is partly their flatness, as with Keds and Vans. However ballet pumps, which have no string or heel, have other specific problems. "As the shoe has no fastening device, it relies on the toes to keep the shoe on, causing an awkward gait ,this leads to short-and long-term problems such as calluses ,heel and knee pain." WEDGES AND STILETTOS These shoes can also cause problems with gait, They may look good, but the heels on these are so high they can force the wearer's body weight forward, making them very unstable. Teens who wear these shoes regularly are also in danger of joining those millions of women with constant back pain. SCHOOL SHOES So what do podiatrists have on their wish list, especially for everyday wear? Something in a natural, breathable fabric, with a string to hold it on, with a small heel and a deep toe-box that does not press the toes, such as Clark's, Marks & Spencer or Rhino. If your teen insists on wearing 'bad' shoes, get them some simple foot orthotics in the shoes. These support and correct the movement of the foot and, properly fitted by a podiatrist, can often transform their walk and halt the damage.
[EX A]:
Of all the shoes mentioned in the passage, which can cause the worst problems?