Which of the following would be an example of vicarious classical conditioning?

a. As a young child, Tony frequently observed his older ­sisters jump around and scream whenever any of them saw a spider, as they were very afraid of them. Subsequently, Tony experiences feelings of fear when he sees a spider.
b. Tommy is told about a new product from a close friend and decides to buy it for himself.
c. A cat responds to the sound of a bell because it sounds similar to a bell it hears on the television.
d. Tonja watches her grandfather check the air pressure in her bike tire and then use a hand pump to add air to the tire. She is later able to check the air pressure and pump up the tire herself.

a