John Watson and Rosalie Rayner (1920) Conditioned an 11-Month-Old Baby

John Watson and Rosalie Rayner (1920) conditioned an 11-month-old baby named Albert to fear a white rat by pairing it with a loud noise. Albert already feared the loud noise. After the conditioning had taken place, the researchers also found that Albert was afraid of furry white and grey objects, such as a rabbit and a Santa Claus mask. The fact that Albert was afraid of these additional items demonstrated that

A) stimulus generalization had occurred
B) discrimination had occurred
C) extinction had occurred
D) higher-order conditioning had occurred