Think carefully about what would happen to the market-clearing prices and quantities of e-cigarettes in the U.S. under the following hypothetical scenarios.

a) Scientific evidence emerged that e-cigarettes are able to help smokers quit smoking successfully and this information has been accurately communicated to the public.

b) The covid-19 pandemic disrupted the supply chain of e-cigarettes, which increased per unit transportation cost of e-cigarettes.

c) The federal government imposed a $1 per pack excise tax on cigarettes.

d) The federal government took cannabis off the Schedule 1 list, and subsequently, many states that previously did not allow cannabis recreational use among their adult residents started to allow it.