I have worked in a couple of different industries recently, but the new survey only allows a single choice for
Can those be changed to checkboxes?
The question is phrased (emphasis mine):
In your question, you state (again, emphasis mine):
That might be the case, but you imply that you only work in a single industry now, which is exactly what the survey is asking for.
It wants to know where you work, not where you've worked.
If you are currently working in two or more industries at the same time, then I'd see this as being valid, but I think that's probably not the use case for most people.
Even if it was, chances are that they spend the majority of their time concentrating on one over the other, in which case, that would be the piece of data that the survey is trying to capture.
Finally, if you are overly concerned about not contaminating the poll data, there is always the option of not taking the survey (I'd hope that's the prime motivating factor here).