Answer:
A. Make sure you cite a reliable source.
Explanation:
B. There are many unreliable materials that could be simply "printed". Being printed does not show reliability.
C. Since Wikipedia can be edited by anyone may find it untrustable to use.
D. Many .com websites can be a fake commericial website that has "fake" news.
Therefore A is the best choice for quoting a statistic. Citing from a reliable source will allow for trustability to be gained by the readers for your work.
