Bristol Public School Foundation had available of donor restricted funds in excess of $$200,000.$ The donor stipulates that the principle can be invested conservatively and cannot be spent. Income derived from the funds can be used for projects approved by the foundation board. The foundation decided to invest this money temporarily until it needs the funds for the restricted purpose. The donors had made no specific stipulations regarding investment earnings but the foundation board had voted to use the earnings on the projects for which the gift had originally been restricted. At year$-$end, the securities had a fair value of $$200,500.$ The appropriate way to recognize the change in fair value is

A$.$ Debit Investment $$500$; Credit Restricted revenue $$500.$

B$.$ Debit Investment $$500$; Credit Unrestricted revenue $$500.$

C$.$ No entry should be made until the securities are sold.

D$.$ Debit Investment $$500$; Credit Grant revenue $$500.$