By the Early Twenty-First Century, What Was the Status of Union

By the early twenty-first century, what was the status of union membership in the private sector?

A) Union membership steadily increased from 1900 to 2000.
B) Military troops were used to prevent unions from meeting.
C) Less than 10 percent of workers in the private sector belonged to unions.
D) These private-sector unions were more powerful than ever.
E) Unions had been completely banned.