Question

Which of the following is a false reason for parallel lines not being used for long distances?

(a) Cost factor

(b) Signal Attenuation

(c) Number of transmission channels

(d) Low speed

I had been asked this question in an interview for job.

Enquiry is from Parallel and Serial Transmission in portion Digital Communication Techniques of Avionics

Answer 1

Correct answer is (d) Low speed

For explanation I would say: One of the major disadvantages of using parallel transmission for long distance is that laying the data bus is costly. To cover a distance of 10km for an 8 bit system, we need a cable of 80km length. Parallel data are usually faster than serial since all the bits are transmitted simultaneously.