Over the long run,real earnings per worker can increase only at about the same rate as the economy's rate of growth of:

A) total output.
B) stock of capital.
C) output per worker.
D) international trade.

Real earnings per worker are directly linked to output per worker, and the economy's rate of growth is largely determined by growth in output per worker. Therefore, real earnings per worker can increase only at about the same rate as the economy's rate of growth of output per worker. Growth in the stock of capital or international trade may have an impact on the rate of growth of output, but ultimately it is output per worker that drives real earnings.