The correct answer is: C. Saltpetre
The Danish East India Company built a factory in Patna in 1774 for the trading of saltpetre. Saltpetre is a mineral that is used in the manufacture of gunpowder. It is also used in the production of fertilizers and explosives.
The Danish East India Company was a trading company that was founded in 1616. The company was granted a monopoly on trade with India by the Danish king. The company operated for over 200 years and played an important role in the development of Danish trade and commerce.
The Danish East India Company built a number of factories in India, including the one in Patna. The factory in Patna was built to trade in saltpetre, which was a valuable commodity at the time. The factory was successful and helped to make the Danish East India Company a profitable enterprise.
The Danish East India Company was dissolved in 1845. However, the company’s legacy can still be seen in the factory that it built in Patna. The factory is now a museum that tells the story of the Danish East India Company and its role in the development of India.
The other options are incorrect because they are not commodities that were traded by the Danish East India Company. Spices, cotton cloth, and tea were all traded by other European trading companies, but they were not traded by the Danish East India Company.