This question is a big fat non sequitur !
The wavelength of radio waves traveling through vacuum only depends on the frequency that the radio station is licensed to broadcast on, (which had better be the frequency of the transmitter that they buy and use, or they're in big trouble).
The wavelength does NOT depend on the type of modulation that's used to put information onto the signal.
An amateur radio (ham) operator may very well start out using FM to talk over his radio to somebody else, and then for some reason they may decide to switch to AM. They can do that without ANY change in the wavelength of their transmissions.
Now, in the USA and many other countries, it so happens that all AM stations are licensed by their governments to transmit their programs on a channel somewhere between 500 KHz and 1.6 MHz, and all FM stations are licensed by their governments to transmit their programs on a channel somewhere between 88 MHz and 108 MHz. (And THAT's what the radio receivers in these countries are built to receive.)
Then we might say that all of the AM stations are grouped around 1 MHz, and all of the FM stations are grouped around 100 MHz. The FM frequencies are very roughly 100 times the AM frequencies, so the AM wavelengths are very roughly 100 times the FM wavelengths. That's <em>choice (3)</em> .
But please don't get the idea that it has anything to do with using AM or FM technology. It's just a matter of where in the spectrum the government decided to put the AM stations and where they put the FM stations.
For that matter . . . An analog TV station uses an AM signal for the picture and an FM signal for the sound, and it all goes in the same channel, with just about the same wavelengths !
