The Table Below Shows the Percentage of the Labour Force

The table below shows the percentage of the labour force accounted for by males and females over a two-decade period.Assume that real GDP is equal to potential in each of the given years.
% of Labour Force
TABLE 30-4
-Refer to Table 30-4.Suppose that for each year listed the unemployment rate among males is 5% while it is 7% among females.What is the economy's NAIRU in 1975?

A) 5.0%
B) 5.5%
C) 5.6%
D) 5.7%
E) 5.8%