There are some aspects of Under Armour that make them unique. Through doing a little research, you will find that they specialize in what they call HeatGear, ColdGear, and AllSeasonGear. They have categorized all of their inventory to meet the needs of their customers for all weather and all season. You may want to try on some of their clothing to see how it feels. You can talk about comfort, style and how they accommodate all of their customers needs through their innovative design. Just make sure you've tried out their gear before the interview. Product knowledge will score you extra points!
"I believe that your brand is so popular because it was founded by, and is driven, through the genuine needs of an athlete. Also, you have some incredible lines such as your All Season Gear, HOVR shoe line, and many celebrity endorsements that make you stand out from the rest."