Final answer:
In a national economy, no country produces all the goods and services that its people want. Economies rely on trade and specialization to meet the diverse demands of their population.
Step-by-step explanation:
The correct answer is b) Want.
In a national economy, no country produces all the goods and services that its people want. This is because every individual has unique desires and preferences, and it is impossible for any economy to meet all these demands.
For example, if a person wants a specific type of food that is not produced in their country, they will need to rely on trade to obtain it from a country that does produce it. Similarly, if someone wants a particular brand of clothing that is not manufactured in their own country, they will have to import it from a country where it is produced.
In conclusion, economies cannot produce all the goods and services that people want, so they rely on trade and specialization to meet the diverse demands of their population.