Answer:
The answer is A. Stimulus generalization.
Explanation:
Stimulus generalization occurs when the conditioned response the a specific stimulis is also presented with other similar stimulus. In the passage, the stimulus was orange juice, but it generalised to grape juice.
In a famous experiment by behaviourist John B. Watson, a child who was conditioned to fear a white rat also showed fear when in front of similar objects, such as a fur coat or a rabbit.