अधिगम का 'प्रयास एवं त्रुटि का सिद्धांत' किसके द्वारा दिया गया था?

In a classroom, a teacher repeatedly pairs a particular sound with handing out homework. Over time, students react to the sound with disappointment even before homework is given. Which learning theory best explains this scenario?

In Pavlov's classical conditioning experiment, in which stage is the conditioned response (CR) elicited directly by the conditioned stimulus (CS)?