Depending on what the grade forgiveness policy is at your school, you may want to consider taking them. D's can really hurt a GPA and bumping the grade to a C or B may improve your GPA. HOWEVER, if the rest of your grades are stellar, don't bother and mention it in your essay. Tell them that you don't think your GPA fully reflects your potential due to these D's in History...because you thought you might like history, took some classes, hated the classes and did horribly...and now you've learned and grown from this expereince....blah, blah, blah. Plus, schools will look at your science GPA as well, so if that's higher than your overall GPA, they will take notice and you're all good!