On its December 31, 2017 balance sheet, Calhoun Company appropriately reported a $10,000 debit balance in its Fair Value Adjustment account. There was no change during 2018 in the composition of Calhouns portfolio of debt investments held as available-for-sale debt securities. The following information pertains to that portfolio: Security Cost Fair Value at 12/31/18 X $130,000 $160,000 Y $100,000 $90,000 Z $175,000 $175,000 Total $405,000 $375,000 The amount of unrealized loss on these debt securities should be included in Calhoun's stockholders' equity section of the balance sheet at December 31, 2018 is _______.

A. $40,000

B. $0

C. $30,000

D. $20,000