The following data are available for a heating, ventilating, and air conditioning (HVAC) vent manufacturer started as a new company four years ago when the construction cost index was 120: Current liabilities - $150,000 Operating income - $295,000 NBV long-term assets (end year 3) - $840,000 Current assets - $180,000 Gross book value * - $1,200,000 Estimated total useful life *10 years Age of assets * 4 years Construction cost index end of year 4 * = "of long-term assets at historical cost" - 135 What is the current cost annual depreciation in year 4 dollars? A. $165,000 B. $135,000 C. $120,000 D. $84,000 E. $106,667