I am using Adobe Acrobat Pro x. I am stuck on writing some Javascript.

I have a drop down box labeled Grade and 4 images labeled A,B,C and D. What I would like is if the drop down box has A Selected Then image A will be at 100% opacity while B,C and D are at 35% opacity.

And then the same for each picture, if B is selected image B is 100% rest are 35% opacity so on and so forth.

If drop down selection is blank all are at 0% capacity