单选题 The passage provides information that would answer which of the following questions?

• (A) What are some of the structural and chemical properties that nanotechnologists strive to create when they mold molecules?
• (B) Why are the techniques of scanning probe microscopy necessary to the production of objects and molecule arrays in the top-down method?
• (C) Which is more important to the future of nanotechnology, scientists' use of the theoretical principles or practical experience?
• (D) Has the nanometer scale been considered easier than the angstrom scale for nanotechnologists to work with?
• (E) For what reasons do bottom-up nanotechnologists prefer to work with three- dimensional chemical systems that cohere according to the rules of chemical interactions?