The age/earnings proles below shows the potential income streams for a high school graduate. Stream A represents future earnings if the individual enters the labor force with no further education. Stream B represents future earnings if the individual attends college before entering the labor force. Which area represents the earnings differential between a person entering the labor market with a high school degree and a person entering the labor market with a college degree? Earnings (dollars) Income stream A Income stream B Costs (dollars) OB OD 0c OA