At the beginning of the year, the permanent fund of Rapid City had an investment portfolio with a historical cost of $300,000 and a fair value of $330,000. There were no purchases or sales of securities during the year. At year end the portfolio had a fair value of $360,000. At the end of the year Rapid City will account for this increase in fair value in which of the following ways?
a) Credit Investment income, $30,000.
b) Credit Investment income, $60,000.
c) Credit Fund Balance, $30,000.
d) No entry is made to recognize increase in fair value.