Which Scenario Best Exemplifies the Principles of Classical Conditioning

Which scenario best exemplifies the principles of classical conditioning?

A) Andrew is a toddler and is in the middle of toilet training. When Andrew uses the toilet, his mom gives him a sticker as a reward. Andrew really likes stickers and begins using the toilet on a regular basis so that he can get more of them.
B) Suzanne is a young professional and is a smoker. During her breaks, she goes outside to smoke with several of her coworkers. After several weeks of doing so, Suzanne finds that the smell of their secondhand smoke makes her feel ill and, as a result, has no desire to smoke anymore.
C) Tyrone is a teenager and has been saving his money to buy a car. His school class at school is planning a three-day trip to Florida, and Tyrone would really like to go. However, his dad told him that in order to go he would have to pay his own way. Tyrone decides to forego the trip so he does not deplete his car fund.
D) Gretchen is child and is friends with the neighbor girl. Gretchen has a beautiful dollhouse that the neighbor enjoys playing with. Gretchen knows the neighbor's family cannot afford to buy such a dollhouse, so she lets the neighbor play with the dollhouse whenever she wants.