The government has warned of possible travel disruptions this winter because the primary chemical used to keep airport runways free of snow and ice is scarce. There are effective alternative chemicals. However, they are environmentally hazardous and thus require special exemptions from the ban on their use. So if the government issued such exemptions to cold-weather airports, travelers would not have to face the warned-of travel disruptions.

Which of the following is an assumption on which the argument depends?

There will be a sufficient amount of the alternative chemicals to supply all the airports that need them.

The number of winter storms bringing snow and ice this winter is forecast to be no greater than normal.

The government has an established policy of issuing exemptions from the alternative-chemical ban when the primary chemical is scarce.

The supply of regularly used chemicals that was available before this winter's shortage has been enough to keep flights moving in past winters.

If disruptions of flights occur during the winter in question, they will not be caused by a lack of the chemicals used to keep runways free of snow and ice.


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