Answer :
In general, it was an increase in the service industry that led to a decline in labor union membership, since many of these workers don't need representation.
The correct answer is D) service industry.
An increase in the service industry created a decline in labor union membership.
Labor Unions had more presence in the industrial and agriculture industries. People gathered and formed labor to demand better working conditions and the respect of their rights. The times when Unions were formed were times of conflicts for cheap paid jobs an infrahuman working conditions. But with the coming of the service industry many years after the factories and agriculture industries, things changed. The increase in the service industry created a decline in labor union membership. The entertainment industry, hospitality industry, banking, and software corporations are an example of services that are not represented by Unions.