Please answer the following question: Here's a logic test: Joe rolls a spray can on its side across the concrete floor in his garage, then he takes the spray can in side and rolls it across his bear skin floor. The can comes to stop after a shorter distance on the bear skin rug than it does on the concrete floor, which leads him to the determination that the smoother surface is (A) the concrete floor (B) bear skin rug. Choose the answer between "bear skin rug" and "concrete floor".
A:
bear skin rug