I can't remember the last time I had to read and re-read the Qotd so many times. It definitely made more sense after I read the question, read the answers and re-read the question for the 4th time :-). As I had never used sparse columns or column sets, I figured out the answer from reading up on column sets and then re-reading the question and picking up that the word "Individual" was probably the key. To Hugo's point, I think it would have been a little easier had the question and answers been worded differently.

Regardless, I learned something today. Thanks for the question.