In a paper published in the Journal of Human Resources (2016), Andrews, Li and Lovenheim find that at the top of the earnings distribution, community college and nonflagship four-year graduates earn the same amount. Lower in the earnings distribution, community college graduates earn much less than non-flagship four-year graduates. Is this pattern consistent with a human capital model, a signaling model in which one's highest degree attained is the only signal, or both? Explain.