Help! I have trouble understanding how to arrive at the correct answer for the following question:

NATLA Inc. purchased several investments in debt securities during 2018, its first year of operations. The following information pertains to these securities. The fluctuations in their fair values are not considered permanent.

Held to Maturity Securities:	Fair Value 12/31/2017			Fair Value 12/31/2018			Amortized Cost 12/31/2017			Amortized Cost 12/31/2018
ABC Co. Bonds	$	375,000		$	400,000		$	367,500		$	360,000
Trading Securities:	Fair Value 12/31/2017			Fair Value 12/31/2018			Cost
DEF Co. Bonds	$	48,000		$	59,500		$	66,000
GEH Inc. Bonds	$	47,000		$	77,000		$	39,000
IJK Inc. Bonds	$	44,000		$	38,500		$	32,900
Available for Sale Securities:	Fair Value 12/31/2017			Fair Value 12/31/2018			Cost
LMN Co. Bonds	$	130,500		$	150,400		$	140,000

What would be the balance in NATLAs accumulated other comprehensive income with respect to these investments in its 12/31/2019 balance sheet (ignore taxes)?

A) $55,100.

B) $26,500.

C) $10,400.

D) None of these answer choices are correct.

Note: can you please explain how to arrive at the correct answer C? Please provide your calculations and explanation on Word or Excel as handwriting is usually difficult to read. I would greatly appreciate it.