When taking a MOOC in calculus the exercises contain 5 options to select from. I then solve the question and select the option that matches my answer. Obviously only one of the options is correct. But there are (quite a few) times where my solution is wrong even though it is one of the available options.
My question is, how does a maths teacher know how to create wrong options that are as plausible as the correct answer?
I've found these two good questions but I am wondering how would an educator come up with wrong answers in general.