According to Solow's Growth Accounting Formula for the United States

According to Solow's growth accounting formula for the United States, a 2 percent annual growth rate in labor, a 4 percent annual growth rate in capital, and a 5 percent annual growth rate in GDP mean that overall productivity must be growing at an annual rate of

A) 1.4 percent.
B) 1.6 percent.
C) 2.4 percent.
D) 3.6 percent.
E) none of the above.