"The vote" is already accepted. We're showcasing "the vow" as the best answer because it's not the most immediate translation.
If you input "the vote" and it wasn't accepted by the system, you've suffered from a glitch. Next time it happens, please print screen the red screen of doom and sen (d it as an attachment to this bug report form: https://support.duolingo.com/hc/en-us/requests/new
Edit: I didn't even notice this was in the Politics section; if it were in the "Spiritual" or any other section, it would make more sense to have "the vow" upfront for the reasons I stated earlier. I've now switched the positioning of the answers and "The vote" is now the answer that will show up in exercises as the best answer, and the one you'll be asked to translate from English to Portuguese from now on.
After you finish this tree, you can indulge in the arduous way of keeping "golden" all the lessons and reach the maximum level, which is 25; Or even do what they call a "reverse tree" that is to make English for Portuguese speakers. If you have the time, I would still advise you to determine a learning agenda that would include watching a few hours of video lessons, reading at least one journal in Portuguese a week, watching some Portuguese novel or series, choosing a book of your interest as reading In the medium term and when you feel safe, get contact from some native speakers to eventual conversations (there are social networks specialized in this) to take some certification of the language, and several other activities that will depend on your time and level of Portuguese. Not to mention still that you can launch into other languages of Latin origin. The closest to Portuguese is Spanish, which has its pros and cons. I advise you to do this only if you already have a more consolidated intermediate level (B2).