After a conditioned response has been extinguished and a period of time has passed, may occur in response to the original conditioned stimulus; however, it will be in form. higher-order conditioning; stronger generalization; weaker spontaneous recovery; weaker generalization; stronger

The correct answer is spontaneous recovery and weaker. Spontaneous recovery is being defined as a phenomenon of learning and memory by which is defined as the reemergence of an extinguish conditioned response that happen previously after a certain delay and that it will get weaker if the original conditioned stimulus occur when it comes to response.