Q.Which transmission medium carries data as pulses of light and offers very high speed over long distances?
(A) Twisted-pair cable
(B) Coaxial cable
(C) Optical-fibre cable
(D) Radio waves

The clue is that the signal is carried by light, not by electricity or by waves through the air.

Section e explains the communication media. Optical-fibre cable carries data as pulses of light through very thin strands of glass or plastic, giving very high speed, very large capacity (bandwidth), and long distance, and it is immune to electrical interference. So option (C) is correct. …

Do not pick coaxial cable simply because it is better than twisted pair. The defining clue here is 'pulses of light', which only optic …