In March 2016 American employers added 215,000 positions to their payrolls, bringing the average job increase for the year to more than 200,000 per month. At the same time, though, the official unemployment rate went up from 4.9% to 5.0%. What is a likely explanation? A. "Discouraged workers" re-entered the labor force B. The labor force has decreased C. The number of volunteering positions in the U.S. economy has decreased D. The number of people working part-time has increased