如何在CodeIgniter中进行动态下拉?

I've been rebuilding my site using CodeIgniter. I am currently making the sign up page and am looking for the most efficient/ strategic way to make a dynamic drop down. This is a social network for the Cystic Fibrosis community. That being said, when registering there is a drop down that ask your relation to CF. I've been rebuilding my site using CodeIgniter.