题目

The sun rises above the Artic Ocean (北冰洋). Across the frozen sea, a white bear moves slowly.The bear stops and sways (摇晃) his head from side to side. There is nothing to see but endless ice and red sky. Then his powerful nose senses what his eyes cannot: a beluga whale is nearby.The bear follows the smell and spots a large hole in the ice where a small white whale is swimming. He silently walks towards the hole, then stops, standing still. The whale does not see the bear, whose white fur makes him appear invisible (看不见的) against the ice.Finally, the whale swims close to where函数y=xn的图象经过点（2，16），则n的值是（ ）A．B．C．2D．4