ANS:C - 55

The approximate height of a blast furnace having a useful volume of 2000 m^3 is about 55 metres. Blast furnaces are tall, cylindrical structures used for smelting iron ore and producing molten iron. They are typically characterized by their large height-to-diameter ratios. The useful volume of a blast furnace is a measure of its internal capacity, which includes the space available for charging raw materials, molten metal, and gases. While the exact dimensions of blast furnaces can vary, a useful volume of 2000 m^3 would correspond to a furnace with significant height. Blast furnaces of this size commonly have heights in the range of 50 to 60 meters. Therefore, the most appropriate approximate height for a blast furnace with a useful volume of 2000 m^3 is 55 metres.