is the set up used in the transimiision of information from one place to another. The present day communication systems are electrical, electronic or optical in nature. Three parts of a communication system are: Transmitter: Communication Channer and Receiver. A signal is defined as a single valued function of time. This function has a unique value at every instant of time. Most of the speech or information signals cannot be transmitted directly over long distances. They have to be modulated suitably and then trasmitted. Communication channer carries the modulated wave from transmitter to receiver. The air, transmission lines and free space are the common communication channels. the reciever consisits of a pickup antenna, a with the help of the above passage, choose the most appropriate alternative to each of the following questions: Communication systems may beA. electricalB. electronicC. opticalD. any of the above