Assume an economy exists for 3 periods. The government's budget balance in period 1 is $150 and the present discounted value of the government's budget balance in period 2 is -$110. If the initial debt is equal to $200, the present discounted value of the government's budget balance in period 3 must be
a. $160
b. -$100
c. -$160
d. $100
Show work.