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