Ken Used to Drool at the Smell of Peanut Butter

Multiple Choice

Ken used to drool at the smell of peanut butter cookies as they baked, and he couldn't wait to sink his teeth into that first cookie. However, Ken's new roommate makes terrible peanut butter cookies, and the smell of them baking is no longer associated with a wonderful taste experience. Consequently, Ken finds that the smell of the cookies no longer makes him drool in anticipation. Which classical conditioning process does this illustrate?

A) extinction
B) second-order conditioning
C) avoidance
D) spontaneous recovery