One factor that contributed to the growth in the share of population employed in the united states between 1960 and 2010 was increased: a. labor union participation. b. female labor force participation. c. male labor force participation. d. minimum wages.

B. female labor force participation

Explanation:

The labor force are the people within the country which are hired or actively looking for a job.

For the relevant time period, female participation in the labor force increase to 73.5 millions from 18.4 millions in 1950

In percent of labor force, this is an increase to 46.8% from 30%

Also, from the total female population, there were only 35% of the women actively looking for a job or hired in the past, while by 2000 more than three-quarters of the females where  hired or looking for a job (in the labor force)

Therefore, we can conclude this is the main factor for which the labor increased.