Some sources of electromagnetic waves in free space are listed.
a radio wave transmitter
a source of X-rays
a wavelength radar transmitter
a light-emitting diode that emits red light
Which list gives the sources in order of increasing wavelength, from left to right, of the waves emitted by the sources?
1 3
4
2
2 4
1
3
2 4
3
1
3 1
4
2