Which of the following is an example of external (subjective) factor which affect attention?

Step 1: Recall definitions. Classical conditioning (Pavlov): Neutral stimulus paired with unconditioned stimulus to produce conditioned response (involuntary). Operant conditioning (Skinner): Voluntary behavior shaped by consequences (reinforcement/punishment). Step 2: Analyze options for classical conditioning example. Typical options include: a. Child gets dessert for cleaning room (operant: positive reinforcement). b. Dog salivates to bell after food pairing (classical: conditioned response). c. Rat presses lever for food (operant: positive reinforcement). d. Gold star for homework (operant: positive reinforcement). Step 3: Identify match. Only option b demonstrates stimulus-stimulus association leading to involuntary response, without voluntary action required. b