I notice that you say "it was unlikely there would be that many choices" for both 16 and 66. For 66 I interpret your reply as "there are likely to be fewer than 66 different choices", but I am having trouble making sense of the answer for 16.
If there is a choice #17, I assume that choices #1 through #16 exist as well (hence it is not only "not unlikely", but known to be true that there was a #16). However, were some numbers skipped, for good reason? or alternatively, did the funny choice only make sense if it was the last one on the list (for example, "all of the above")?I misread the 16 as 166, I think. There were about 25 choices. I doubt there would have been as many as 50, much less more.
There was nothing significant about the placement of this option on the list. It was not the last one. The others were skipped, because none of them made me laugh, and they shouldn't have.