I was a few questions in to the first level when I was asked, “what longitude line forms the circle that divides Earth into two hemispheres?”. I responded with meridian, since the prime meridian follows the longitude of the Earth while the equator follows the latitude. I took a screenshot to ensure I wasn’t reading the question incorrectly and verified my original answer on nationalgeographic.org in a direct quote, “The Earth can also be divided into hemispheres along meridians, or lines of longitude“. The question was marked incorrect with, “equator” as the correct answer. Just don’t want to falsely inform people.