单项选择题
A．infinite space, by definition, can exist but cannot be observed from an external reference point
B．in order for there to be an outside to the universe, the ultimate physical reality must be a Euclidean planar space
C．one cannot observe the edge of any object, including the universe, except by using a perspective external to it
D．the universe can always be redefined to include what is beyond an absolute reference point
E．the universe is a hypersphere which must be embedded in higher-dimensional space than that given by Euclidean geometry