In 2011,the U.S.unionization Rate Was

In 2011,the U.S.unionization rate was:

A) 5.5 percent,down by nearly one-half of the rate in the mid-1950s.
B) 14.8 percent,up by about one-fourth of the rate in the mid-1950s.
C) 11.8 percent,down by more than one-half of the rate in the mid-1950s.
D) 21.2 percent,down by 4 percentage points from the mid-1950s.