MySQL - Many to Many relationship, or one to many with additional columns
Basically you can only use
Question - TagsQuestion - Tags

With the bridge table, if one tags is set for many questions.
It wuld also save some space, if you have a lot of questions.
The sencond option has the problem, that if you wqant all tags t be displayed you need five INNER JOINs, for every Tag one, while you can make the same query with two joins, with the first option..
Overall, the first option with bridge table, is the more flexible and space consuming option.