Correct Answer: US dollar

Solution : The correct answer is d) US dollar

The US dollar is widely considered a leading currency in international trade and finance. It is commonly used as a reserve currency by central banks around the world, and many international transactions, including commodities pricing and major financial transactions, are denominated in US dollars. The US dollar's prominence in global trade and financial markets is due to factors such as the size and stability of the US economy, the depth and liquidity of US financial markets, and the widespread acceptance of the US dollar as a medium of exchange.