Answer:
Explanation:
Circadian rhythms are the mechanism that invokes change in behavior and mental status according to cycle of daily life.This change procedure works according to the light that persist in surroundings of the individual i.e- darkness in night or brightness at day etc.
According to the question, Janet might be uncomfortable to adjust in London because is used to daily circadian rhythms of Toronto time.She has well established light related daily work which can create difficulty in change according to London time.
Other options are incorrect because plane's speed, disorder related with melatonin-production and insomnia are not the causes for difficultly in adjustment in London.