Sunflowers track the sun's movement across the sky when they are young.
Why it is true
This process is called heliotropism. Young sunflower buds face east in the morning and follow the sun to the west, but mature flowers permanently face east.
Source: Botany
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.