Final answer:
To calculate the depreciation for year 2 using straight-line depreciation, divide the difference between the cost and salvage value by the useful life.
Step-by-step explanation:
To calculate the depreciation for year 2 using straight-line depreciation, you need to divide the difference between the cost of the computer system and its salvage value by the useful life in years.
The difference between the cost and salvage value is $55,000 - $10,000 = $45,000.
The depreciation for year 2 would be $45,000 / 5 = $9,000.
Therefore, the correct answer is C. $9,000.