Populations tend to grow over time, meaning there are more workers. In order to maintain a constant level of worker productivity, the total amount of capital available to them must:

a. increase at a rate at least equal to population growth.

b. decrease slightly, as this will motivate employees to work harder.

c. increase at a rate less than the rate of population growth.

d. increase at a rate equal to the rate of inflation.

e. stay constant over time, as inflation and population growth tend to cancel each other out.