The correct answer is: A. Modem
A modem is a device that converts digital signals to analog signals and vice versa. This is necessary for communication between computers and other devices over telephone lines, which are designed to carry analog signals.
A transducer is a device that converts energy from one form to another. For example, a microphone converts sound waves into electrical signals, and a loudspeaker converts electrical signals into sound waves.
Punched paper tape is a data storage medium that consists of a long strip of paper with holes punched in it. The holes represent data, which can be read by a computer.
Punched cards are similar to punched paper tape, but they are made of stiff paper and have rectangular holes punched in them. Punched cards were once widely used for data storage and input, but they have been largely replaced by electronic media.
E. None of the above is not the correct answer, as it does not specify a device that converts one type of signal into another.