Australia is the only continent with no active volcanoes.
Why it is true
Because it does not sit on the edge of a tectonic plate, mainland Australia has been geologically quiet for thousands of years, unlike Antarctica or Africa.
Source: Geology
Would you rather be asked first?
This is the reading side of the site, so the answer is in the sentence above — that is the whole point of it. Test yourself works the other way round: the question comes on its own, and the fact and the explanation only appear once you have answered.