Questions 17 to 20 are based on the following report about the new development in computer technology. You now have 20 seconds to read Questions 17 to 20.
The new technology is not applicable at present because

A. the new device is smaller than a grain of salt.
B. the new device does not have vast data storage capacity.
C. the new device is limited by the wavelength of light.
D. the new device can not switch on and off repeatedly.