Which is an example of post hoc?

A train always passes after the railroad crossing alarm sounds and the gates come down. Therefore the railroad crossing causes the train to pass. I wore my purple sweater and my team won against all the odds. Therefore I am going to wear that sweater to every game. Most divorced couples go to see a therapist before they separate. Therefore going to see a therapist will increase the chances that you will get a divorce. Children of divorce, on average, perform poorer academically. Therefore, if you get a divorce you will hurt your child's chances of going to college. Since we moved in together she has become very depressed. I feel like I've ruined her life. Since I stopped smoking we haven't had an argument. Who knew the answer could have been so simple?