Answer:
Mobile Applications and Smart Phones are Complements
Smart Phones and Conventional Phones are Substitutes
Mobile Applications and Conventional Phones are substitutes.
Step-by-step explanation:
Complement goods are goods that can be used or consumed together. E.g. car and gas. A car would not work without gas. A rise in price of a good leads to a fall in demand of the complement good.
Subsituite goods rival one another in consumption. They can be used in place of another good.
A rise in price of a good leads to a rise in demand of the other good.
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