A business has an accounting year that finishes on 31 December. An office building with a useful life of 40 years was bought on 1 January 2010 for $400\,000$. Its residual value is expected to be nil. Depreciation is calculated by the straight-line method. On 1 January 2018, the office building was revalued to $480\,000$. What is the net book value of the office building on 31 December 2019?
- A$360\,000$
- B$450\,000$
- C$456\,000$
- D$465\,000$