Not so. I found mag extremely helpful for 4 or 5 of my symptoms, but relatively neutral for all of the others. Without multiple choices, I wouldn't have been able to post a complete answer, thereby skewing the poll and misleading other posters/readers.
I agree w/ @pamojja .... magnesium is multi-faceted, as would be the list of the things it either helps or does nothing for, or, in some members, may actually serve to worsen some conditions. A one-choice answer gives very little latitude considering the broad range of the poll as posted.
Looks like @Sarah94 may want to switch off the option of "Multiple votes are allowed". In this particular poll, you only need one vote.
You cannot logically satisfy more than one of those answer options simultaneously.
I think the orginal question is too wide, to allow for a truthful one vote only.