Jojo,
I agree completely with your point of view, and think it's fabulous that you have the opportunity to present your opinion. May I suggest that you run a quick online search for references? For example, I googled "food reward children" and came up with a bunch of hits, including this one from Michigan State University, which seems fairly succinct and on-topic
http://www.tn.fcs.msue.msu.edu/foodrewards.pdf I'm not sure whether you disagree with food as a reward completely (if you can call what McD's serves "food") or whether it's the fact that it's food that's so unhealthy. In my opinion, it's both that are bad.
Good luck! Wish I could hear you on the radio!
~S from MD
