Which statement best describes the projected benefit obligation measurement?

Select one:

a. Actuarial present value of the benefits attributed to employee service rendered to date, as measured by the benefit formula using current salary levels.

b. Actuarial present value of the benefits attributed to employee service rendered to date, as measured by the benefit formula using estimated future salary levels.

c. Actuarial present value of the benefits attributed to employee service rendered to date, as measured by the benefit formula using current salary levels, limited to vested benefits.

d. Actuarial present value of the benefits attributed to employee service rendered to date, as measured by the benefit formula using future salary levels, limited to vested benefits.