"what did john b. watson and rosalie rayner demonstrate with their studies of little albert"

The answer is emotion can be a conditioned response. What does that mean? It means that it can refer to a detailed educated behavior or a technique frequently used in classical or Pavlovian conditioning research.  It is an "emotional response" that outcomes from classical conditioning, typically from the link of a comparatively neutral stimulus with a painful or fear-inducing unconditional stimulus. As a consequence, the previously neutral stimulus provokes fear.