The tomato is legally a vegetable in the US.
Why it is true
In 1893, the US Supreme Court decided that, for customs import tax purposes, the tomato would be classified as a vegetable.
Source: US Supreme Court
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.