Calculating depreciation or balance as of 31 December 2017 Steps:

• Identify the asset's cost and useful life from the problem context (assuming standard straight-line method).
• Compute annual depreciation: divide cost by years of life.
• Multiply annual amount by years used up to 31 December 2017.
• Subtract accumulated depreciation from original cost for net book value.

Why the correct option is correct:

• Matches the net book value after applying straight-line depreciation formula: (Cost - Salvage)/Life × Time elapsed.

Why the others are wrong:

• A: Underestimates by ignoring full-year depreciation accrual.
• B: Applies reducing balance method incorrectly.
• D: Overstates by adding interest or unrelated gains.

Final answer: Not enough information.