问题如下：
During an economic recovery, a lagging unemployment rate is most likely attributable to:
选项：
A.businesses quickly rehiring workers.
B.new job seekers entering the labor force.
C.underemployed workers transitioning to higher-paying jobs.
解释：
B is correct.
In an economic recovery, new job seekers return to the labor force, and because they seldom find work immediately, their return may initially raise the unemployment rate.
考点：Unemployment
解析：因为在经济刚开始不景气的时候，企业主会通过减少工人工作小时数的方法调节生产，只有当经济进一步衰退时才会考虑裁员，所以B选项说法正确。
经济不景气的时候企业主无意培训新员工，工人也很难找到培训再就业的机会，所以A,C选项都错误。
对于C的理解有疑义，经济复苏，工厂不会马上招人，而是会提高工作时间，那么underemployer会选择待遇更好的职业。
