From time to time, we see a new question from a new user like this one, passive vs active treatment.
When asked to include more context or clarify some points, (s)he posts an answer using a different user name instead of editing the question like this, https://english.stackexchange.com/questions/338689/passive-vs-active-treatment/338724#338724.
What would be the best course of action that we should take?
Advise the OP to visit Help Center > My Account and follow the guideline to (1) merge the two accounts, (2) delete the answer which is not an answer, (3) edit the question.
Flag it for moderator's attention as @ColleenV commented when it seems obvious that they're the same user.
Edit the question myself and flag the answer as "not an answer" for deletion.