Which of the Following Is a Reason That Long-Term Jobs

Which of the following is a reason that long-term jobs can only partially be explained by the accumulation of firm-specific human capital?

A) Long-term jobs also require general human capital.
B) Some workers' real earnings decline over time.
C) Firm-specific human capital only partially explains the level of a worker's output.
D) Workers only acquire firm-specific human capital for the first few weeks of a job.
E) Only high-ability workers are able to acquire firm-specific human capital.