MULTIPLE CHOICE (identify the one best answer and provide explanations): Consider an economy in which each worker has one machine and one unit of natural resources. Assume these inputs are fixed, and so is the worker's human capital. But there has been an improvement in technology. We can surely conclude that productivity has increased if:

a. the amount of goods and services produced from each hour of the worker's time increases.

b. the amount of goods and services produced by the worker increases relative to a worker in another country.

c. if the amount of goods and services produced by the worker in a given year increases.

d. all of the above.

e. none of the above.