Which of the following signal types has the narrowest bandwidth?

Continuous Wave (CW), commonly known as Morse code, simply turns a radio frequency carrier on and off. Because it does not need to transmit the complex audio frequencies of the human voice or video images, it requires a very narrow bandwidth—typically only about 150 Hz. By comparison, SSB voice requires about 2,400 to 3,000 Hz, FM voice takes up 10,000 to 15,000 Hz, and slow-scan TV requires a bandwidth similar to SSB. CW's extremely narrow bandwidth concentrates the transmitter's energy efficiently, making it unmatched for weak-signal conditions.