What is used for communication by humans over long distances?
A Greek letter electricity airplanes kinetic energy trains sign language photons messengers
A B C D E F G H
Telephone lines conduct electricity.
Electricity is used for communication by humans over long distances. 
What is used for communication by humans over long distances? (A) A Greek letter (B) electricity (C) airplanes (D) kinetic energy (E) trains (F) sign language (G) photons (H) messengers