Palin expects the only option to be taught to children is abstinence. Which obviously failed in her own home. Which could even be considered a laughable hypocrisy when you compare conception dates of her first child and her marriage date.
You can't tell children to say NO. Teenagers are going to do it whether you want them to or not. The best thing is to teach sex ed and make them responsible and educated about their choices and the long term effects it can have on them and their bodies. (Pregnancy, STDs, etc..)