单选题 The "ancient notion" (line 14) to which the author refers to is the idea that

• (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