Comments in Drop Down Box dependent on number selected in adjacent cell

I'm at my wits end! I've been searching and searching and searching!

I have been asked by my supervisor to make a performance review template a little bit more user friendly.

Basically what I have is a drop own list in cells in one column (various cells with the same drop down menu) that you select from either 0-10 in a drop down box.

I have another cell which I want to have a drop down box with text comments that you select from when. Only problem is the comments different dependent on the ranking score you give a person (the number selection in the previously mentioned cell from 0-10). So if you have a score between 9-10 in the cell then the comments box will give you certain comments to choose, 7-8 different comments and so on and so forth.

Help! I have no idea where to start