'A Conditioned stimulus' is elucidated as the stimulus that was previously neutral eventually leads to evoke a learned response with training. Such a stimulus is contradictory to unconditioned or naturally occurring stimulus which triggers a specific response naturally while the former elicits a response through learning from the various factors.
As per the question, the 'opening of refrigerator' exemplifies a 'conditioned stimulus' as it evokes a learned response from the 'dog' as it runs to the kitchen every time 'refrigerator is opened'. Therefore, 'it demonstrates a conditioned stimulus' as Jasmine learns with time that 'every time the door is opened, he gets some food'.
"A. Did You ask dad if he was finished reading that newspaper before You Cut It up for your science <span>project?" uses the demonstrative properly. Although the others are in common usage. </span><span />
