At the Beginning of the Year, the Permanent Fund of Rose

At the beginning of the year, the permanent fund of Rose 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 the end of the year the portfolio had a fair value of $360,000. At year-end, the city s 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 should be made to recognize an increase in fair value.