【单选题】

According to the passage, which of the following is true concerning optical computers
A．(A) Researchers have not yet discovered a means of transporting photons more efficiently.

B．(B) Their primary limitation is the density of connections required between electronic microchip gates.
C．(C) Their accuracy level is poor at 8 to 11 bits, but still superior to that Of electronic computers.
D．(D) They invariably rely on electronic circuits to preprocess input data for computation.
E．(E) Both analog and digital forms of optic computing are presently being developed by scientists.