Find the odd number / letters / word from the given alternative.

Telescope
Transistor
Taperecorder
Telephone

The answer is C. Tape recorder.

A telescope is an optical instrument that uses lenses to make distant objects appear closer. A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power. A telephone is an electronic device used to transmit and receive sound over a distance. A tape recorder is an electronic device used to record and play back sound on magnetic tape.

Of the four options, only the tape recorder is not a device that uses electricity. The other three options all use electricity to operate.