Answer:
The answer is: A) better or enhanced technology, along with accumulating capital; these economies are growing because technology, unlike capital, is subject to increasing returns.
Explanation:
Capital ,as a factor of production, is limited by the "Law of Diminishing Marginal Returns
". This concept states that at certain point, using an additional factor of production will result in a smaller increase of the total output.
For example, if you have a machine in a factory and you increase the other factors of production (labor and materials), the output will be limited by the total possible output of the machine. Once it works 24 hours a day, seven days a week, and 52 weeks per year, it will reach the maximum output.
The only way you can bypass this law is by the introduction of new and better technologies, e.g. the only way to increase output in the factory is to get a bigger or better machine.