In 2021, Cromwell Corporation purchased bonds of Oliver Company at par for $300,000 and classified the investment as available-for-sale. In 2022, the market value declined to $200,000. In 2023, the market value of the investment rose to $230,000, and the investment was sold. How much should Cromwell record as a realized gain or loss in its determination of net income for 2023?
a. $0

b. $30,000 gain 

c. $70,000 loss

d. $100,000 loss