I believe question ID 5491 is incorrect. Here is the question and possible answers: "
What is the Linnean name of the domestic apple tree?
1) Malus americana
2) Appelus delectica
3) Malus pumila
4) Pomus domestica"
The question’s correct answer is listed as 3, Malus pumila. This name is accepted as synonym for the common apple tree, but the most commonly used Linnean (i.e., scientific name) in the literature is Malus domestica. If you simply google “scientific name for common apple tree”, you get Malus domestica. The International Plant Names Index (IPNI) also suggests Malus domestica is the approved name: Malus domestica | International Plant Names Index. Wikipedia also lists Malus domestica as the main name with M. pumila as a synonym: Apple - Wikipedia. Very technically speaking, the question has the correct answer because the other choices presented are wrong, but the answer is not technically correct overall. In scientific etymology, names are reviewed at the international congress meetings. The latest decision conserved the name Malus domestica over Malus pumila (see: https://onlinelibrary.wiley.com/doi/abs/10.12705/663.15; full paper available on Sci hub or from me by request).
Based on this evidence, I suggest that answer 1 be changed to “Malus domestica” and selected as the correct answer.