Answer:
1. smartphone apps and flash drives are substitutes, and smartphone apps and smartphones are complements
Explanation:
Complements are goods that are consumed together. If the price of one of the goods increases, the demand for the other good increases. This indicates that smartphone and smartphone apps are complements.
Substitutes are goods that can be used in place of each other. If the price of one good falls, the consumer demands more of that good and less of the subsituite goods. This shows that smartphone apps and flash drives are substitutes.
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