well, they put more weight on orgo classes than other classes, so it would have been nice if he had improved vastly.
It was totally worth it, it just didn't happen. That doesn't mean he shouldn't have taken those.
I would probably have thought the same to improve those C's
When retaking a class you better be absolutely certain that you will earn an A, otherwise you will do way more harm to your app than if you were to not retake.
Ouch. I will never retake a class that I got a C in. I mean.. you did get a C before in that class. Only time I would even retake is if I am doing a post-bach and have not been accepted to dental school after applying.
The only thing you can do is getting an amazing chem and ochem score on the DAT, and have a very good reason for why you kept on getting Cs in your chemistry classes.