【单选题】

The primary purpose of the passage is to

A、indicate some possible technological benefits to the development of new and varied techniques in nanotechnology
B、argue that science involving the macroscopic tends to be exponentially more difficult than the science of the microscopic
C、defend the use of the bottom-up approach of building molecules as more efficient relative to the top-down approach
D、distinguish two different approaches in nanotechnology and comment on their differences and similarities
E、correct the misconception that the benefits of nanotechnology are likely to be seen in the near future