Dynamic references to classes in AS3

Hope someone can help here… as alway, I’ve dug around for an answer, but in this case nothing directly relevant seems to have fetched up…

I have four movie clips in my library that are defined as classes: Option0, Option1, Option2 and Option3. I have four buttons that pass a different value from 1-4 to a function. I want to add the clip to the display list that relates to the passed value.

In AS2 it would go something like:

this.attachmovie[“option”+currentVal, “newOption”, this.getNextHighestDepth()];

How should I go about doing this in AS3?