Answer:
D. spontaneous recovery
Explanation:
Based on the information provided in regards to the situation at hand it seems that Jane's nausea best illustrates spontaneous recovery. This is a phenomenon discovered by Ivan Pavlov which refers to the re-appearance of a conditioned response thought to have been gone after a significant delay. Which is what is happening since Jane suddenly began having nausea (conditioned response) after having entered the waiting room a couple of decades later.