Rainwater contains small amounts of vitamin B12.
Why it is true
Bacteria present in the atmosphere and soil produce this vitamin, which is then swept into clouds and falls with precipitation, benefiting plants and terrestrial ecosystems.
Source: Atmospheric Chem
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.