Rathke, Inc. has a defined-benefit pension plan covering its 50 employees. Rathke agrees to amend its pension benefits. As a result, the projected benefit obligation increased by $2,400,000. Rathke determined that all its employees are expected to receive benefits under the plan over the next 5 years. In addition 20% are expected to retire or quit at the end of each year, beginning at the end of year 1. Assuming that Rathke uses the years-of-service method of amortization for prior service cost, the amount reported as amortization of prior service cost in one year after the amendment is: $800,000, $640,000, $240,000, or $480,000