If a company has an underfunded defined-benefit pension plan: A. no payment may be made to retirees until the company deposits all of the necessary assets into the pension fund. B. the difference between fund assets and amounts owed to retirees will still be paid by the federal Pension Benefit Guaranty Corporation. C. the value of the ABO (but not of the PBO) must be precisely the same as the amount of assets set aside to pay pension benefits. D. All of the above are true. E. None of the above is true.