Choice "C" is correct. The cost of goods sold is calculated as follows:

The write-off of obsolete inventory is treated as an operating loss and not as cost of goods sold.Choice "d" is incorrect. The $34,000 write off of inventory is subtracted, not added to inventory.
Choice "b" is incorrect. Obsolete inventory is not included in cost of goods sold. It is deducted from inventory and included in unusual gains or losses on the income statement. Total reduction in inventory is $184,000, but $34,000 is not included in cost of goods sold.
Choice "a" is incorrect. Purchases reflect costs of goods sold on a cash basis, not on an accrual basis.