FM Bandwidth

I have a couple of issues with this question.

The first issue is that I'm pretty sure "bandwidth" is not the correct term in this context. FM is not a bandwidth; it's a method of encoding information in a carrier wave (by varying the instantaneous frequency of the wave, as opposed to the amplitude – which is the case in AM broadcasting). Bandwidth is defined (by dictionary.com) as "the smallest range of frequencies constituting a band within which a particular signal can be transmitted without distortion." I'm not an expert in this field, but I don't think this is the same as the range of frequencies over which the wave is (or can be) broadcast.

Electronics notes.com talks of "a typical broadcast FM signal" having a bandwidth of approximately 180 kilohertz for "98% of the power". In other words (if I understand this correctly, which is by no means a given), any particular signal uses a bandwidth of (maybe) a couple of hundred kilohertz within the total band (which covers about 20 megahertz - about 100 times as much). This is why we have governmental regulations as to the range of frequencies that any individual broadcaster is allowed to use.

Wikipedia talks about "the FM broadcast band", which seems to me to be a much better term than "bandwidth" for what the question is about; the Federation of American Scientists states that "The frequency band for FM radio is about 88 to 108 MHz."

This question should maybe have read, "Which method of encoding is used for radio broadcasts in the frequency band 87.5 to 108 megahertz?"

If you think that's too technical, I'd just say ... this is supposed to be the Science round.

The second issue I have with the question is that there are very few answers that can possibly be correct. As well as FM we have AM (as already mentioned) and ... well that's about it, unless you think something like "short wave", "medium wave" or "long wave" is a possible answer. But these are all just subdivisions of the AM frequency band.

And anyway ... no radio station ever tires of telling us what part of the FM frequency band it uses. BBC Radio 2, for example, is "88 to 91 FM."

Sorry if this offends anyone, but I just can't imagine anyone getting this question wrong.

Incidentally: 87.5 to 108 megahertz is the range of frequencies used in Western Europe, Australia and Africa. The US range is virtually the same (88 to 108 MHz), but in Japan and Eastern Europe they are significantly different. For details, refer to Wikipedia.