Earth is not a perfect sphere — it's a geoid.
Why it is true
Earth is slightly flattened at the poles and wider at the equator due to rotation. The actual highest point is Mount Chimborazo.
Source: ESA
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.