On January 1, 2021, PT XYZ has: plan assets of 250,000 and the same amount of defined benefit obligations. During 2021, the service cost is 27,500, the discount rate is 10%, the actual and expected return from plan assets is 25,000, the contribution is 20,000, and the benefits paid are 17,500. How much is PT XYZ's defined benefit obligation balance at the end of 2021?

a. 277,500 b. 285,000 c. 302,500 d. 27,500