Unrealized Holding Gains and Losses Are Recognized on Trading Securities

Unrealized holding gains and losses are recognized on trading securities at the end of each year,based on

A) the difference between the purchase price and the market value of the security at the end of the year
B) the difference between the carrying value and the market value of the security at the end of the year
C) the difference between the purchase price and the carrying value of the security at the end of the year
D) the average of the purchase price and the market value of the security at the end of the year
E) the difference between the market value of the security last year and the market value of the security this year