Do I use the offset function here?

This seems like I should be able to use the offset function on this case but I can't seem to get it to do what I need.

In the sample workbook, each row represents 1 week. I have Class Names listed in column C showing the class that will be starting in a given week. In column D the number of weeks until the graduation week. I am trying to add a formula to column E which will display the Class Name that will graduate that week based on the length of the class in column D.

Thank you for any guidance you can provide.