Answer:
D
Explanation:
If NASA had constructed a Space Shuttle without knowing if it would be safe for its passengers, there could be many casualties. So they would test it beforehand using a model, to make sure that it will be safe and sturdy for when they build it.
The answer to your question is A
Productive Resources are resources used to make goods and services.
Therefore the best possible option is the last one - Factors that are used to make goods and services.
