A New T-Shirt Company Opens a Store Not Far from Your

A new T-shirt company opens a store not far from your college. They also have a website that allows for purchase of most of the items they stock in store, but you've heard several of your friends complain that they can't navigate the site very well from their smartphones. Which of the following has the T-shirt company failed to do?

A) generate interest for their product
B) ensure compatibility with mobile devices
C) optimize website design and functionality for mobile devices
D) simplify payment options for mobile users