:) Maybe they thought all the emotion aroused by our completely justified righteous indignation at this blatantly unfair question would help us remember the tricky distinction between la metro (subway) and il metro (the metre). I'm not mollified, but I have to admit that it probably worked for me. ;)
Seeing as so many sentences have dictionary hints that are totally wrong, they shouldn't be putting trick questions like this in. It's confusing enough with the poor quality audio, incorrect pronunciation and dodgy word suggestions...
Duolingo, please teach me the word for an underground transport system in the 'Transport' section, rather than the 'Measurements' section - k thanx bai :)
notwithstanding the pedagogical intent of distinguishing the word by the article, if the wrong word is listed under the "hover", that is just sloppy work and poor teaching. The "hover" should be intended as an aid, not as a trick question or a distraction causing some 30 responses.